addftinfo(1)                General Commands Manual               addftinfo(1)

Name
       addftinfo - add font metrics to troff fonts for use with groff

Synopsis
       addftinfo [-asc-height n] [-body-depth n] [-body-height n]
                 [-cap-height n] [-comma-depth n] [-desc-depth n]
                 [-fig-height n] [-x-height n] resolution unit‐width font

       addftinfo --help

       addftinfo -v
       addftinfo --version

Description
       addftinfo  reads  an  AT&T troff font description file font, adds addi‐
       tional font metric information required by GNU troff(1), and writes the
       combined result to the standard output.  The information added  is  de‐
       rived  from the font’s existing parameters and assumptions about tradi‐
       tional troff names for characters.  Among the font  metrics  added  are
       the  heights  and depths of characters (how far each extends vertically
       above and below the baseline).  The resolution and unit‐width arguments
       should be the same as the corresponding parameters in  the  DESC  file.
       font  is  the  name  of the file describing the font; if font ends with
       “I”, the font is assumed to be oblique (or italic).

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       All other options change parameters that are used to derive the heights
       and depths.  Like the existing quantities in the font description file,
       each  value  n  is in scaled points, inches/resolution for a font whose
       type size is unit‐width; see groff_font(5).

       -asc-height n
              height of characters with ascenders, such as “b”, “d”, or “l”

       -body-depth n
              depth of characters such as parentheses

       -body-height n
              height of characters such as parentheses

       -cap-height n
              height of uppercase letters such as “A”

       -comma-depth n
              depth of a comma

       -desc-depth n
              depth of characters with descenders, such as “p”, “q”, or “y”

       -fig-height
              height of figures (numerals)

       -x-height n
              height of lowercase letters without ascenders such as “x”

       addftinfo makes no attempt to use the specified parameters to infer un‐
       specified parameters.  If a parameter is  not  specified,  the  default
       will be used.  The defaults are chosen to produce reasonable values for
       a Times font.

See also
       groff_font(5), groff(1), groff_char(7)

groff 1.23.0                      2 July 2023                     addftinfo(1)
───────────────────────────────────────────────────────────────────────────────
afmtodit(1)                 General Commands Manual                afmtodit(1)

Name
       afmtodit  - adapt Adobe Font Metrics files for groff PostScript and PDF
       output

Synopsis
       afmtodit [-ckmnsx] [-a slant] [-d device‐description‐file]
                [-e encoding‐file] [-f internal‐name] [-i italic‐correction‐
                factor] [-o output‐file] [-w space‐width] afm‐file map‐file
                font‐description‐file

       afmtodit --help

       afmtodit -v
       afmtodit --version

Description
       afmtodit adapts an Adobe Font Metric file, afm‐file, for use  with  the
       ps and pdf output devices of troff(1).  map‐file associates a groff or‐
       dinary  or special character name with a PostScript glyph name.  Output
       is written in groff_font(5) format  to  font‐description‐file,  a  file
       named for the intended groff font name (but see the -o option).

       map‐file should contain a sequence of lines of the form
              ps‐glyph groff‐char
       where  ps‐glyph  is the PostScript glyph name and groff‐char is a groff
       ordinary (if of unit length) or special (if longer)  character  identi‐
       fier.   The  same  ps‐glyph  can occur multiple times in the file; each
       groff‐char must occur at most once.  Lines starting with “#” and  blank
       lines  are  ignored.  If the file isn’t found in the current directory,
       it is sought in the devps/generate subdirectory of the default font di‐
       rectory.

       If a PostScript glyph is not mentioned in map‐file, and a groff charac‐
       ter name can’t be deduced using the Adobe Glyph List (AGL,  built  into
       afmtodit),  then afmtodit puts the PostScript glyph into the groff font
       description file as an unnamed glyph which can only be accessed by  the
       “\N”  escape  sequence in a roff document.  In particular, this is true
       for glyph variants named in the form “foo.bar”; all  glyph  names  con‐
       taining  one or more periods are mapped to unnamed entities.  Unless -e
       is specified, the encoding defined in the AFM file (i.e., entries  with
       non‐negative  codes)  is  used.   Refer  to  section “Using Symbols” in
       Groff: The GNU Implementation of troff, the groff  Texinfo  manual,  or
       groff_char(7),  which describe how groff character identifiers are con‐
       structed.

       Glyphs not encoded in the AFM file (i.e., entries indexed as “-1”)  are
       still  available in groff; they get glyph index values greater than 255
       (or greater than the biggest code used in the AFM file in the  unlikely
       case  that  it is greater than 255) in the groff font description file.
       Unencoded glyph indices don’t have a specific order; it is best to  ac‐
       cess them only via special character identifiers.

       If the font file proper (not just its metrics) is available, listing it
       in  the  files  /usr/share/groff/1.23.0/font/devps/download  and  /usr/
       share/groff/1.23.0/font/devpdf/download enables it to  be  embedded  in
       the output produced by grops(1) and gropdf(1), respectively.

       If  the  -i  option is used, afmtodit automatically generates an italic
       correction, a left italic correction, and a  subscript  correction  for
       each  glyph  (the significance of these is explained in groff_font(5));
       they can be specified for individual glyphs by adding to  the  afm‐file
       lines of the form:
              italicCorrection ps‐glyph n
              leftItalicCorrection ps‐glyph n
              subscriptCorrection ps‐glyph n
       where ps‐glyph is the PostScript glyph name, and n is the desired value
       of  the  corresponding parameter in thousandths of an em.  Such parame‐
       ters are normally needed only for italic (or oblique) fonts.

       The -s option should be given if the font is  “special”,  meaning  that
       groff  should  search  it  whenever a glyph is not found in the current
       font.  In that case, font‐description‐file should be listed as an argu‐
       ment to the fonts directive in the output device’s DESC file; if it  is
       not  special,  there is no need to do so, since troff(1) will automati‐
       cally mount it when it is first used.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -a slant
              Use  slant as the slant (“angle”) parameter in the font descrip‐
              tion file; this is used by groff in the positioning of  accents.
              By  default afmtodit uses the negative of the ItalicAngle speci‐
              fied in the AFM file; with true italic fonts it is sometimes de‐
              sirable to use a slant that is less than this.  If you find that
              an italic font places accents over base glyphs too  far  to  the
              right, use -a to give it a smaller slant.

       -c     Include  comments  in  the font description file identifying the
              PostScript font.

       -d device‐description‐file
              The device description file is desc‐file rather than the default
              DESC.  If not found in the current directory, the  devps  subdi‐
              rectory  of the default font directory is searched (this is true
              for both the default device description file and  a  file  given
              with option -d).

       -e encoding‐file
              The  PostScript font should be reencoded to use the encoding de‐
              scribed in enc‐file.  The format of  enc‐file  is  described  in
              grops(1).  If not found in the current directory, the devps sub‐
              directory of the default font directory is searched.

       -f internal‐name
              The internal name of the groff font is set to name.

       -i italic‐correction‐factor
              Generate  an  italic correction for each glyph so that its width
              plus its italic correction is equal to  italic‐correction‐factor
              thousandths  of an em plus the amount by which the right edge of
              the glyph’s bounding box is to the right of its origin.  If this
              would result in a negative italic correction, use a zero  italic
              correction instead.

              Also generate a subscript correction equal to the product of the
              tangent of the slant of the font and four fifths of the x‐height
              of  the  font.   If  this would result in a subscript correction
              greater than the italic correction, use a  subscript  correction
              equal to the italic correction instead.

              Also  generate  a left italic correction for each glyph equal to
              italic‐correction‐factor thousandths of an em plus the amount by
              which the left edge of the glyph’s bounding box is to  the  left
              of  its  origin.  The left italic correction may be negative un‐
              less option -m is given.

              This option is normally needed only  with  italic  (or  oblique)
              fonts.   The  font description files distributed with groff were
              created using an option of -i50 for italic fonts.

       -o output‐file
              Write to output‐file instead of font‐description‐file.

       -k     Omit any kerning data from the groff font; use  only  for  mono‐
              spaced (constant‐width) fonts.

       -m     Prevent  negative  left italic correction values.  Font descrip‐
              tion files for roman styles distributed with groff were  created
              with “-i0 -m” to improve spacing with eqn(1).

       -n     Don’t  output  a ligatures command for this font; use with mono‐
              spaced (constant‐width) fonts.

       -s     Add the special directive to the font description file.

       -w space‐width
              Use space‐width as the with of inter‐word spaces.

       -x     Don’t use the built‐in Adobe Glyph List.

Files
       /usr/share/groff/1.23.0/font/devps/DESC
              describes the ps output device.

       /usr/share/groff/1.23.0/font/devps/F
              describes the font known as F on device ps.

       /usr/share/groff/1.23.0/font/devps/download
              lists fonts available for embedding within the PostScript  docu‐
              ment (or download to the device).

       /usr/share/groff/1.23.0/font/devps/generate/dingbats.map
       /usr/share/groff/1.23.0/font/devps/generate/dingbats-reversed.map
       /usr/share/groff/1.23.0/font/devps/generate/slanted-symbol.map
       /usr/share/groff/1.23.0/font/devps/generate/symbol.map
       /usr/share/groff/1.23.0/font/devps/generate/text.map
              map  names  in  the  Adobe Glyph List to groff special character
              identifiers for  Zapf  Dingbats  (ZD),  reversed  Zapf  Dingbats
              (ZDR),  slanted symbol (SS), symbol (S), and text fonts, respec‐
              tively.  These map‐files are used to produce the  font  descrip‐
              tion files provided with groff for the grops output driver.

Diagnostics
       AGL name 'x' already mapped to groff name 'y'; ignoring AGL name
       'uniXXXX'
              You  can disregard these if they’re in the form shown, where the
              ignored AGL name contains four  hexadecimal  digits  XXXX.   The
              Adobe  Glyph  List  (AGL) has its own names for glyphs; they are
              often different from groff’s special character names.   afmtodit
              is  constructing a mapping from groff special character names to
              AGL names; this can be a one‐to‐one or many‐to‐one mapping,  but
              one‐to‐many  will not work, so afmtodit discards the excess map‐
              pings.  For example, if x is *D, y is Delta, and z  is  uni0394,
              afmtodit  is telling you that the groff font description that it
              is writing cannot map the groff special character \[*D]  to  AGL
              glyphs Delta and uni0394 at the same time.

              If  you  get a message like this but are unhappy with which map‐
              ping is ignored, a remedy is to craft  an  alternative  map‐file
              and re‐run afmtodit using it.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  Section “Using Symbols”  may  be
       of  particular  note.   You  can  browse  it  interactively  with “info
       '(groff)Using Symbols'”.

       groff(1), gropdf(1), grops(1), groff_font(5)

groff 1.23.0                      2 July 2023                      afmtodit(1)
───────────────────────────────────────────────────────────────────────────────
chem(1)                     General Commands Manual                    chem(1)

Name
       chem - embed chemical structure diagrams in groff documents

Synopsis
       chem [--] [file ...]

       chem -h
       chem --help

       chem -v
       chem --version

Description
       chem produces chemical structure diagrams.   Today’s  version  is  best
       suited  for  organic  chemistry  (bonds, rings).  The chem program is a
       groff preprocessor like eqn, pic, tbl, etc.  It  generates  pic  output
       such  that  all chem parts are translated into diagrams of the pic lan‐
       guage.

       If no operands are given, or if file is “-”, chem  reads  the  standard
       input  stream.   -h  and --help display a usage message, whereas -v and
       --version display version information; all exit.

       The program chem originates from the  Perl  source  file  chem.pl.   It
       tells  pic  to include a copy of the macro file chem.pic.  Moreover the
       groff source file pic.tmac is loaded.

       In a style reminiscent of eqn and pic, the chem diagrams are written in
       a special language.

       A set of chem lines looks like this

              .cstart
              chem data
              .cend

       Lines containing the keywords .cstart and .cend start and end the input
       for chem, respectively.  In pic context, i.e., after the call  of  .PS,
       chem  input  can optionally be started by the line begin chem and ended
       by the line with the single word end instead.

       Anything outside these initialization lines is copied  through  without
       modification;  all  data  between the initialization lines is converted
       into pic commands to draw the diagram.

       As an example,

              .cstart
              CH3
              bond
              CH3
              .cend

       prints two CH3 groups with a bond between them.

       If you want to create just groff output, you must run chem followed  by
       groff with the option -p for the activation of pic:

              chem [file ...] | groff -p ...

Language
       The  chem input language is rather small.  It provides rings of several
       styles and a way to glue them together as  desired,  bonds  of  several
       styles, moieties (e.g., C, NH3, ..., and strings.

   Setting variables
       There  are  some  variables that can be set by commands.  Such commands
       have two possible forms, either

              variable value

       or

              variable = value

       This sets the given variable to the argument value.  If more  arguments
       are  given only the last argument is taken, all other arguments are ig‐
       nored.

       There are only a few variables to be set by these commands:

       textht arg
              Set the height of the text to arg; default is 0.16.

       cwid arg
              Set the character width to arg; default is 0.12.

       db arg Set the bond length to arg; default is 0.2.

       size arg
              Scale the diagram to make it look plausible at point  size  arg;
              default is 10 point.

   Bonds
       This

              bond [direction] [length n] [from Name|picstuff]

       draws a single bond in direction from nearest corner of Name.  bond can
       also  be double bond, front bond, back bond, etc.  (We will get back to
       Name soon.)

       direction is the angle in degrees (0 up, positive clockwise) or  a  di‐
       rection  word like up, down, sw (= southwest), etc.  If no direction is
       specified, the bond goes in the current direction (usually that of  the
       last bond).

       Normally  the  bond  begins  at  the  last  object placed;  this can be
       changed by naming a from place.  For instance, to make a  simple  alkyl
       chain:
              CH3
              bond                (this one goes right from the CH3)
              C                   (at the right end of the bond)
              double bond up      (from the C)
              O                   (at the end of the double bond)
              bond right from C
              CH3

       A  length  in  inches  may be specified to override the default length.
       Other pic commands can be tacked on to the end of a  bond  command,  to
       created dotted or dashed bonds or to specify a to place.

   Rings
       There  are  lots  of rings, but only five‐ and six‐sided rings get much
       support.  ring by itself is a six‐sided ring; benzene  is  the  benzene
       ring  with  a  circle  inside.  aromatic puts a circle into any kind of
       ring.

              ring [pointing (up|right|left|down)] [aromatic] [put Mol at n]
                   [double i,j k,l ... [picstuff]

       The vertices of a ring are numbered 1, 2,  ...  from  the  vertex  that
       points  in the natural compass direction.  So for a hexagonal ring with
       the point at the top, the top vertex is 1, while  if  the  ring  has  a
       point at the east side, that is vertex 1.  This is expressed as

              R1: ring pointing up
              R2: ring pointing right

       The ring vertices are named .V1, ..., .Vn, with .V1 in the pointing di‐
       rection.  So the corners of R1 are R1.V1 (the top), R1.V2, R1.V3, R1.V4
       (the  bottom),  etc., whereas for R2, R2.V1 is the rightmost vertex and
       R2.V4 the leftmost.  These vertex names are used for  connecting  bonds
       or other rings.  For example,

              R1: benzene pointing right
              R2: benzene pointing right with .V6 at R1.V2

       creates two benzene rings connected along a side.

       Interior  double  bonds  are  specified as double n1,n2 n3,n4 ...; each
       number pair adds an interior bond.  So the alternate form of a  benzene
       ring is

              ring double 1,2 3,4 5,6

       Heterocycles  (rings  with something other than carbon at a vertex) are
       written as put X at V, as in

              R: ring put N at 1 put O at 2

       In this heterocycle, R.N and R.O become synonyms for R.V1 and R.V2.

       There are two five‐sided rings.  ring5 is pentagonal with a  side  that
       matches the six‐sided ring; it has four natural directions.  A flatring
       is a five‐sided ring created by chopping one corner of a six‐sided ring
       so that it exactly matches the six‐sided rings.

       The description of a ring has to fit on a single line.

   Moieties and strings
       A  moiety  is  a  string of characters beginning with a capital letter,
       such as N(C2H5)2.  Numbers are converted to subscripts (unless they ap‐
       pear to be fractional values, as in N2.5H).  The name of  a  moiety  is
       determined  from the moiety after special characters have been stripped
       out: e.g., N(C2H5)2) has the name NC2H52.

       Moieties can be specified in two kinds.  Normally a  moiety  is  placed
       right  after  the  last  thing mentioned, separated by a semicolon sur‐
       rounded by spaces, e.g.,

              B1: bond ; OH

       Here the moiety is OH; it is set after a bond.

       As the second kind a moiety can be positioned as the first  word  in  a
       pic‐like command, e.g.,

              CH3 at C + (0.5,0.5)

       Here  the  moiety  is CH3.  It is placed at a position relative to C, a
       moiety used earlier in the chemical structure.

       So moiety names can be specified as chem positions  everywhere  in  the
       chem code.  Beneath their printing moieties are names for places.

       The  moiety BP is special.  It is not printed but just serves as a mark
       to be referred to in later chem commands.  For example,

              bond ; BP

       sets a mark at the end of the bond.  This can be used then for specify‐
       ing a place.  The name BP is derived  from  branch  point  (i.e.,  line
       crossing).

       A string within double quotes " is interpreted as a part of a chem com‐
       mand.   It  represents  a  string  that  should be printed (without the
       quotes).  Text within quotes "..." is treated more or less like a  moi‐
       ety except that no changes are made to the quoted part.

   Names
       In  the  alkyl chain above, notice that the carbon atom C was used both
       to draw something and as the name for a place.  A moiety always defines
       a name for a place;  you can use your own names for places instead, and
       indeed, for rings you will have to.  A name is just

              Name: ...

       Name is often the name of a moiety like CH3, but it  need  not  to  be.
       Any name that begins with a capital letter and which contains only let‐
       ters and numbers is valid:

              First: bond
                     bond 30 from First

   Miscellaneous
       The specific construction

              bond ... ; moiety

       is equivalent to

              bond
              moiety

       Otherwise,  each item has to be on a separate line (and only one line).
       Note that there must be whitespace after the semicolon which  separates
       the commands.

       A  period character . or a single quote ' in the first column of a line
       signals a troff command, which is copied through as‐is.

       A line whose first non‐blank character  is  a  hash  character  (#)  is
       treated as a comment and thus ignored.  However, hash characters within
       a word are kept.

       A  line  whose first word is pic is copied through as‐is after the word
       pic has been removed.

       The command

              size n

       scales the diagram to make it look plausible at point size  n  (default
       is 10 point).

       Anything else is assumed to be pic code, which is copied through with a
       label.

       Since  chem is a pic preprocessor, it is possible to include pic state‐
       ments in the middle of a diagram to draw things  not  provided  for  by
       chem  itself.   Such  pic statements should be included in chem code by
       adding pic as the first word of this line for clarity.

       The following pic commands are accepted as chem  commands,  so  no  pic
       command word is needed:

              define Start the definition of pic macro within chem.

              [      Start a block composite.

              ]      End a block composite.

              {      Start a macro definition block.

              }      End a macro definition block.

       The macro names from define statements are stored and their call is ac‐
       cepted as a chem command as well.

   Wish list
       This TODO list was collected by Brian Kernighan.

       Error  checking is minimal; errors are usually detected and reported in
       an oblique fashion by pic.

       There is no library or file inclusion mechanism, and there is no short‐
       hand for repetitive structures.

       The extension mechanism is to create pic macros, but these  are  tricky
       to get right and don’t have all the properties of built‐in objects.

       There  is  no  in‐line chemistry yet (e.g., analogous to the $...$ con‐
       struct of eqn).

       There is no way to control entry point for bonds on groups.  Normally a
       bond connects to the carbon atom if entering from the top or bottom and
       otherwise to the nearest corner.

       Bonds from substituted atoms on heterocycles do not join at the  proper
       place without adding a bit of pic.

       There is no decent primitive for brackets.

       Text (quoted strings) doesn’t work very well.

       A squiggle bond is needed.

Files
       /usr/share/groff/1.23.0/pic/chem.pic
              A collection of pic macros needed by chem.

       /usr/share/groff/1.23.0/tmac/pic.tmac
              A macro file which redefines .PS, .PE, and .PF to center pic di‐
              agrams.

       /usr/share/doc/groff-1.23.0/examples/chem/*.chem
              Example files for chem.

       /usr/share/doc/groff-1.23.0/examples/chem/122/*.chem
              Example files from the chem article by its authors, “CHEM—A Pro‐
              gram  for  Typesetting Chemical Structure Diagrams: User Manual”
              (CSTR #122).

Authors
       The GNU version of  chem  was  written  by  Bernd  Warken  ⟨groff-bernd
       .warken-72@web.de⟩.    It  is  based  on  the  documentation  of  Brian
       Kernighan’s original awk version of chem.

See also
       “CHEM—A Program for Typesetting Chemical Diagrams: User Manual” by  Jon
       L.  Bentley,  Lynn W. Jelinski, and Brian W. Kernighan, 1992, AT&T Bell
       Laboratories Computing Science Technical Report No. 122

       groff(1), pic(1)

groff 1.23.0                      2 July 2023                          chem(1)
───────────────────────────────────────────────────────────────────────────────
eqn(1)                      General Commands Manual                     eqn(1)

Name
       eqn - format mathematics (equations) for groff or MathML

Synopsis
       eqn [-CNrR] [-d xy] [-f F] [-m n] [-M dir] [-p n] [-s n] [-T dev]
           [file ...]

       eqn --help

       eqn -v
       eqn --version

Description
       The GNU implementation of eqn is part of the groff(7) document  format‐
       ting  system.   eqn  is a troff(1) preprocessor that translates expres‐
       sions in its own language, embedded in roff(7) input files, into mathe‐
       matical notation typeset by troff(1).  It copies each  file’s  contents
       to  the standard output stream, translating each equation between lines
       starting with .EQ and .EN, or within a pair  of  user‐specified  delim‐
       iters.  Normally, eqn is not executed directly by the user, but invoked
       by  specifying the -e option to groff(1).  While GNU eqn’s input syntax
       is highly compatible with AT&T eqn, the output eqn produces  cannot  be
       processed  by  AT&T  troff; GNU troff (or a troff implementing relevant
       GNU extensions) must be used.  If no file operands  are  given  on  the
       command line, or if file is “-”, eqn reads the standard input stream.

       Unless  the  -R  option is used, eqn searches for the file eqnrc in the
       directories given with the -M option first, then  in  /usr/share/groff/
       site-tmac,  and  finally  in  the  standard macro directory /usr/share/
       groff/1.23.0/tmac.  If it exists and is readable, eqn processes it  be‐
       fore any input files.

       This  man  page primarily discusses the differences between GNU eqn and
       AT&T eqn.  Most of the new features of the GNU eqn input  language  are
       based on TeX.  There are some references to the differences between TeX
       and GNU eqn below; these may safely be ignored if you do not know TeX.

       Three points are worth special note.

       • GNU  eqn  emits  Presentation  MathML  output  when  invoked with the
         “-T MathML” option.

       • GNU eqn does not support terminal devices well, though it may suffice
         for simple inputs.

       • GNU eqn sets the input token “...” as an ellipsis on the  text  base‐
         line,  not  the  three centered dots of AT&T eqn.  Set an ellipsis on
         the math axis with the GNU extension macro cdots.

   Anatomy of an equation
       eqn input consists of tokens.  Consider a form of Newton’s  second  law
       of motion.  The input

              .EQ
              F =
              m a
              .EN

       becomes  F=ma.  Each of F, =, m, and a is a token.  Spaces and newlines
       are interchangeable; they separate tokens but do  not  break  lines  or
       produce space in the output.

       The  following  input  characters  not only separate tokens, but manage
       their grouping and spacing as well.

       { }    Braces perform grouping.  Whereas “e sup a b” expresses  “(e  to
              the  a)  times b”, “e sup { a b }” means “e to the (a times b)”.
              When immediately preceded by a “left” or  “right”  primitive,  a
              brace loses its special meaning.

       ^ ~    are  the  half  space and full space, respectively.  Use them to
              tune the appearance of the output.

       Tab and leader characters separate tokens  as  well  as  advancing  the
       drawing  position  to the next tab stop, but are seldom used in eqn in‐
       put.  When they occur, they must appear at the outermost lexical scope.
       This roughly means that they can’t appear within braces that are neces‐
       sary to disambiguate the input; eqn will  diagnose  an  error  in  this
       event.   (See subsection “Macros” below for additional token separation
       rules.)

       Other tokens are primitives, macros, an argument to either of the fore‐
       going, or components of an equation.

       Primitives are fundamental keywords of the eqn language.  They can con‐
       figure an aspect  of  the  preprocessor’s  state,  as  when  setting  a
       “global” font selection or type size (gfont and gsize), or declaring or
       deleting macros (“define” and undef); these are termed commands.  Other
       primitives  perform  formatting operations on the tokens after them (as
       with fat, over, sqrt, or up).

       Equation components include mathematical variables, constants,  numeric
       literals,  and operators.  eqn remaps some input character sequences to
       groff special character escape sequences for economy in equation  entry
       and  to  ensure  that  glyphs  from  an  unstyled  font  are  used; see
       groff_char(7).

              +   \[pl]                '    \[fm]
              ‐   \[mi]                <=   \[<=]
              =   \[eq]                >=   \[>=]

       Macros permit primitives, components, and other macros to be  collected
       and  referred  to by a single token.  Predefined macros make convenient
       the preparation of eqn input in a form resembling  its  spoken  expres‐
       sion; for example, consider cos, hat, inf, and lim.

   Spacing and typeface
       GNU  eqn  imputes types to the components of an equation, adjusting the
       spacing between them accordingly.  Recognized  types  are  as  follows;
       most  affect  spacing  only, whereas the “letter” subtype of “ordinary”
       also assigns a style.

         ordinary      character such as “1”, “a”, or “!”
           letter      character to be italicized by default
           digit       n/a
         operator      large operator such as “Σ”
         binary        binary operator such as “+”
         relation      relational operator such as “=”
         opening       opening bracket such as “(”
         closing       closing bracket such as “)”
         punctuation   punctuation character such as “,”
         inner         sub‐formula contained within brackets
         suppress      component to which automatic spacing is not applied

       Two primitives apply types to equation components.

       type t e
              Apply type t to expression e.

       chartype t text
              Assign each character in (unquoted) text type t, persistently.

       eqn sets up spacings and styles as if by the following commands.

              chartype "letter"      abcdefghiklmnopqrstuvwxyz
              chartype "letter"      ABCDEFGHIKLMNOPQRSTUVWXYZ
              chartype "letter"      \[*a]\[*b]\[*g]\[*d]\[*e]\[*z]
              chartype "letter"      \[*y]\[*h]\[*i]\[*k]\[*l]\[*m]
              chartype "letter"      \[*n]\[*c]\[*o]\[*p]\[*r]\[*s]
              chartype "letter"      \[*t]\[*u]\[*f]\[*x]\[*q]\[*w]
              chartype "binary"      *\[pl]\[mi]
              chartype "relation"    <>\[eq]\[<=]\[>=]
              chartype "opening"     {([
              chartype "closing"     })]
              chartype "punctuation" ,;:.
              chartype "suppress"    ^~

       eqn assigns all other ordinary and special roff  characters,  including
       numerals  0–9, the “ordinary” type.  (The “digit” type is not used, but
       is available for customization.)  In keeping with  common  practice  in
       mathematical  typesetting,  lowercase, but not uppercase, Greek letters
       are assigned the “letter” type to style them in  italics.   The  macros
       for producing ellipses, “...”, cdots, and ldots, use the “inner” type.

   Primitives
       eqn  supports  without  alteration the AT&T eqn primitives above, back,
       bar, bold, define, down, fat, font, from, fwd,  gfont,  gsize,  italic,
       left,  lineup,  mark,  matrix, ndefine, over, right, roman, size, sqrt,
       sub, sup, tdefine, to, under, and up.

   New primitives
       The GNU extension primitives “type” and chartype are discussed in  sub‐
       section  “Spacing  and typeface” above; “set” in subsection “Customiza‐
       tion” below; and grfont and gbfont in subsection “Fonts” below.  In the
       following synopses, X can be any character not appearing in the parame‐
       ter thus bracketed.

       e1 accent e2
              Set e2 as an accent over e1.  e2 is assumed to be at the  appro‐
              priate  height  for a lowercase letter without an ascender;  eqn
              vertically shifts it depending on e1’s height.  For example, hat
              is defined as follows.

                     accent { "^" }

              dotdot, dot, tilde, vec, and dyad are  also  defined  using  the
              accent primitive.

       big e  Enlarge  the  expression  e; semantics like those of CSS “large”
              are intended.  In troff output, the type size is increased by  5
              scaled points.  MathML output emits the following.

                     <mstyle mathsize='big'>

       copy file
       include file
              Interpolate  the contents of file, omitting lines beginning with
              .EQ or .EN.  If a relative path name, file is sought relative to
              the current working directory.

       ifdef name X anything X
              If name is defined as a primitive or macro, interpret anything.

       nosplit text
              As "text", but since text is not quoted it is subject  to  macro
              expansion; it is not split up and the spacing between characters
              not adjusted per subsection “Spacing and typeface” above.

       e opprime
              As  prime, but set the prime symbol as an operator on e.  In the
              input “A opprime sub 1”, the “1” is tucked under the prime as  a
              subscript  to  the “A” (as is conventional in mathematical type‐
              setting), whereas when prime is used, the “1” is a subscript  to
              the  prime  character.  The precedence of opprime is the same as
              that of bar and “under”, and higher than that  of  other  primi‐
              tives  except  accent  and uaccent.  In unquoted text, a neutral
              apostrophe (') that is not the first character on the input line
              is treated like opprime.

       sdefine name X anything X
              As “define”, but name is not recognized as  a  macro  if  called
              with arguments.

       e1 smallover e2
              As  over,  but reduces the type size of e1 and e2, and puts less
              vertical space between e1 and e2 and the fraction bar.  The over
              primitive corresponds to the TeX \over  primitive  in  displayed
              equation  styles;  smallover corresponds to \over in non‐display
              (“inline”) styles.

       space n
              Set extra vertical spacing around the  equation,  replacing  the
              default  values,  where  n is an integer in hundredths of an em.
              If positive, n increases vertical spacing before  the  equation;
              if negative, it does so after the equation.  This primitive pro‐
              vides  an  interface to groff’s \x escape sequence, but with the
              opposite sign convention.  It has no effect if the  equation  is
              part of a pic(1) picture.

       special troff‐macro e
              Construct  an  object  by  calling  troff‐macro on e.  The troff
              string 0s contains the eqn output for e, and the  registers  0w,
              0h,  0d,  0skern,  and 0skew the width, height, depth, subscript
              kern, and skew of e, respectively.  (The subscript  kern  of  an
              object  indicates  how much a subscript on that object should be
              “tucked in”, or placed to the left relative to a non‐subscripted
              glyph of the same size.  The skew of an object is how far to the
              right of the center of the object an accent over  it  should  be
              placed.)   The  macro  must modify 0s so that it outputs the de‐
              sired result, returns the drawing position to the text  baseline
              at  the  beginning  of e, and updates the foregoing registers to
              correspond to the new dimensions of the result.

              Suppose you want a construct that  “cancels”  an  expression  by
              drawing a diagonal line through it.

                     .de Ca
                     .  ds 0s \
                     \Z'\\*(0s'\
                     \v'\\n(0du'\
                     \D'l \\n(0wu -\\n(0hu-\\n(0du'\
                     \v'\\n(0hu'
                     ..
                     .EQ
                     special Ca "x \[mi] 3 \[pl] x" ~ 3
                     .EN

              We use the \[mi] and \[pl] special characters instead of + and -
              because  they  are part of the argument to a troff macro, so eqn
              does not transform them to mathematical glyphs for us.  Here’s a
              more complicated construct that draws a box  around  an  expres‐
              sion;  the bottom of the box rests on the text baseline.  We de‐
              fine the eqn macro box to wrap the call of the troff macro Bx.

                     .de Bx
                     .ds 0s \
                     \Z'\\h'1n'\\*[0s]'\
                     \v'\\n(0du+1n'\
                     \D'l \\n(0wu+2n 0'\
                     \D'l 0 -\\n(0hu-\\n(0du-2n'\
                     \D'l -\\n(0wu-2n 0'\
                     \D'l 0 \\n(0hu+\\n(0du+2n'\
                     \h'\\n(0wu+2n'
                     .nr 0w +2n
                     .nr 0d +1n
                     .nr 0h +1n
                     ..
                     .EQ
                     define box ' special Bx $1 '
                     box(foo) ~ "bar"
                     .EN

       split "text"
              As text, but since text is quoted, it is not  subject  to  macro
              expansion; it is split up and the spacing between characters ad‐
              justed per subsection “Spacing and typeface” above.

       e1 uaccent e2
              Set e2 as an accent under e1.  e2 is assumed to be at the appro‐
              priate  height for a letter without a descender;  eqn vertically
              shifts it depending on whether e1 has a  descender.   utilde  is
              predefined using uaccent as a tilde accent below the baseline.

       undef name
              Remove  definition  of  macro or primitive name, making it unde‐
              fined.

       vcenter e
              Vertically center e about the math axis, a horizontal line  upon
              which  fraction  bars  and  characters  such  as “+” and “−” are
              aligned.  MathML already behaves this way, so eqn  ignores  this
              primitive  when  producing that output format.  The built‐in sum
              macro is defined as if by the following.

                     define sum ! { type "operator" vcenter size +5 \(*S } !

   Extended primitives
       GNU eqn extends the syntax of some AT&T eqn primitives, introducing one
       deliberate incompatibility.

       delim on
              eqn recognizes an “on” argument  to  the  delim  primitive  spe‐
              cially, restoring any delimiters previously disabled with “delim
              off”.  If delimiters haven’t been specified, neither command has
              effect.   Few  eqn  documents are expected to use “o” and “n” as
              left and right delimiters, respectively.  If  yours  does,  con‐
              sider swapping them, or select others.

       col n { ... }
       ccol n { ... }
       lcol n { ... }
       rcol n { ... }
       pile n { ... }
       cpile n { ... }
       lpile n { ... }
       rpile n { ... }
              The  integer value n (in hundredths of an em) increases the ver‐
              tical spacing between rows, using  groff’s  \x  escape  sequence
              (the  value  has no effect in MathML mode).  Negative values are
              accepted but have no effect.  If more than one n occurs in a ma‐
              trix or pile, the largest is used.

   Customization
       When eqn generates troff input, the appearance  of  equations  is  con‐
       trolled by a large number of parameters.  They have no effect when gen‐
       erating  MathML,  which delegates typesetting to a MathML rendering en‐
       gine.  Configure these parameters with the set primitive.

       set p n
              assigns parameter p the integer value n;  n  is  interpreted  in
              units of hundredths of an em unless otherwise stated.  For exam‐
              ple,

                     set x_height 45

              says  that  eqn  should  assume  that  the  font’s  x‐height  is
              0.45 ems.

              Available parameters are  as  follows;  defaults  are  shown  in
              parentheses.   We  intend  these  descriptions  to be expository
              rather than rigorous.

              minimum_size     sets a floor  for  the  type  size  (in  scaled
                               points) at which equations are set (5).

              fat_offset       The  fat  primitive  emboldens  an  equation by
                               overprinting two copies of the  equation  hori‐
                               zontally  offset by this amount (4).  In MathML
                               mode, components to  which  fat_offset  applies
                               instead use the following.
                                      <mstyle mathvariant='double-struck'>

              over_hang        A  fraction  bar is longer by twice this amount
                               than the maximum of the widths of the numerator
                               and denominator; in other words,  it  overhangs
                               the  numerator and denominator by at least this
                               amount (0).

              accent_width     When bar or under is applied to a single  char‐
                               acter,  the  line is this long (31).  Normally,
                               bar or under produces a line  whose  length  is
                               the width of the object to which it applies; in
                               the  case  of a single character, this tends to
                               produce a line that looks too long.

              delimiter_factor Extensible delimiters produced  with  the  left
                               and right primitives have a combined height and
                               depth  of  at  least  this  many thousandths of
                               twice the maximum amount by which the sub‐equa‐
                               tion that the delimiters enclose  extends  away
                               from the axis (900).

              delimiter_shortfall
                               Extensible  delimiters  produced  with the left
                               and right primitives have a combined height and
                               depth not less than the difference of twice the
                               maximum amount by which the  sub‐equation  that
                               the  delimiters  enclose  extends away from the
                               axis and this amount (50).

              null_delimiter_space
                               This much horizontal space is inserted on  each
                               side of a fraction (12).

              script_space     The width of subscripts and superscripts is in‐
                               creased by this amount (5).

              thin_space       This  amount of space is automatically inserted
                               after punctuation characters.  It also  config‐
                               ures  the  width of the space produced by the ^
                               token (17).

              medium_space     This amount of space is automatically  inserted
                               on either side of binary operators (22).

              thick_space      This  amount of space is automatically inserted
                               on either side of relations.  It  also  config‐
                               ures  the  width of the space produced by the ~
                               token (28).

              x_height         The height of lowercase letters without  ascen‐
                               ders such as “x” (45).

              axis_height      The  height above the baseline of the center of
                               characters such as “+” and “−” (26).  It is im‐
                               portant that this value is correct for the font
                               you are using.

              default_rule_thickness
                               This should be set  to  the  thickness  of  the
                               \[ru] character, or the thickness of horizontal
                               lines produced with the \D escape sequence (4).

              num1             The  over  primitive shifts up the numerator by
                               at least this amount (70).

              num2             The smallover primitive shifts up the numerator
                               by at least this amount (36).

              denom1           The over primitive shifts down the  denominator
                               by at least this amount (70).

              denom2           The smallover primitive shifts down the denomi‐
                               nator by at least this amount (36).

              sup1             Normally  superscripts  are  shifted  up  by at
                               least this amount (42).

              sup2             Superscripts within superscripts or upper  lim‐
                               its  or  numerators  of smallover fractions are
                               shifted up by at least this amount (37).   Con‐
                               ventionally, this is less than sup1.

              sup3             Superscripts   within  denominators  or  square
                               roots or subscripts or lower limits are shifted
                               up by at least this amount  (28).   Convention‐
                               ally, this is less than sup2.

              sub1             Subscripts  are  normally  shifted  down  by at
                               least this amount (20).

              sub2             When there is both a  subscript  and  a  super‐
                               script,  the  subscript  is  shifted down by at
                               least this amount (23).

              sup_drop         The baseline of a superscript is no  more  than
                               this  much below the top of the object on which
                               the superscript is set (38).

              sub_drop         The baseline of a subscript is  at  least  this
                               much  below  the  bottom of the object on which
                               the subscript is set (5).

              big_op_spacing1  The baseline of an upper limit is at least this
                               much above the top of the object on  which  the
                               limit is set (11).

              big_op_spacing2  The  baseline of a lower limit is at least this
                               much below the bottom of the  object  on  which
                               the limit is set (17).

              big_op_spacing3  The  bottom  of an upper limit is at least this
                               much above the top of the object on  which  the
                               limit is set (20).

              big_op_spacing4  The  top of a lower limit is at least this much
                               below the bottom of the  object  on  which  the
                               limit is set (60).

              big_op_spacing5  This much vertical space is added above and be‐
                               low limits (10).

              baseline_sep     The  baselines  of the rows in a pile or matrix
                               are normally this  far  apart  (140).   Usually
                               equal to the sum of num1 and denom1.

              shift_down       The  midpoint  between the top baseline and the
                               bottom baseline in a matrix or pile is  shifted
                               down  by this much from the axis (26).  Usually
                               equal to axis_height.

              column_sep       This much space is added between columns  in  a
                               matrix (100).

              matrix_side_sep  This  much space is added at each side of a ma‐
                               trix (17).

              draw_lines       If non‐zero, eqn draws lines using the troff \D
                               escape sequence, rather than the \l escape  se‐
                               quence  and  the  \[ru] special character.  The
                               eqnrc file sets the default: 1 on ps, html, and
                               the X11 devices, otherwise 0.

              body_height      is the presumed height of an equation above the
                               text baseline; eqn adds  any  excess  as  extra
                               pre‐vertical  line  spacing with troff’s \x es‐
                               cape sequence (85).

              body_depth       is the presumed depth of an equation below  the
                               text  baseline;  eqn  adds  any excess as extra
                               post‐vertical line spacing with troff’s \x  es‐
                               cape sequence (35).

              nroff            If  non‐zero,  then ndefine behaves like define
                               and tdefine is ignored, otherwise  tdefine  be‐
                               haves  like define and ndefine is ignored.  The
                               eqnrc  file  sets  the  default:  1  on  ascii,
                               latin1, utf8, and cp1047 devices, otherwise 0.

   Macros
       In  GNU  eqn,  macros can take arguments.  A word defined by any of the
       define, ndefine, or tdefine primitives followed immediately by  a  left
       parenthesis is treated as a parameterized macro call: subsequent tokens
       up to a matching right parenthesis are treated as comma‐separated argu‐
       ments.   In this context only, commas and parentheses also serve as to‐
       ken separators.  A macro argument is not terminated by a  comma  inside
       parentheses  nested  within  it.  In a macro definition, $n, where n is
       between 1 and 9 inclusive, is replaced by the nth  argument;  if  there
       are fewer than n arguments, it is replaced by nothing.

   Predefined macros
       GNU  eqn  supports  the  predefined  macros  offered  by AT&T eqn: and,
       approx, arc, cos, cosh, del, det, dot, dotdot, dyad,  exp,  for,  grad,
       half,  hat,  if,  inter, Im, inf, int, lim, ln, log, max, min, nothing,
       partial, prime, prod, Re, sin, sinh,  sum,  tan,  tanh,  tilde,  times,
       union, vec, ==, !=, +=, ->, <-, <<, >>, and “...”.  The lowercase clas‐
       sical  Greek letters are available as alpha, beta, chi, delta, epsilon,
       eta, gamma, iota, kappa, lambda, mu, nu, omega, omicron, phi, pi,  psi,
       rho, sigma, tau, theta, upsilon, xi, and zeta.  Spell them with an ini‐
       tial  capital  letter (Alpha) or in full capitals (ALPHA) to obtain up‐
       percase forms.

       GNU eqn further defines the macros cdot, cdots, and  utilde  (all  dis‐
       cussed  above), dollar, which sets a dollar sign, and ldots, which sets
       an ellipsis on the text baseline.

   Fonts
       eqn uses up to three typefaces to set an  equation:  italic  (oblique),
       roman (upright), and bold.  Assign each a groff typeface with the prim‐
       itives  gfont,  grfont,  and gbfont.  The defaults are the styles I, R,
       and B (applied to the current font  family).   The  chartype  primitive
       (see  above) sets a character’s type, which determines the face used to
       set it.  The “letter” type is set in italics; others are set in  roman.
       Use the bold primitive to select an (upright) bold style.

       gbfont f
              Select f as the bold font.  This is a GNU extension.

       gfont f
              Select f as the italic font.

       grfont f
              Select f as the roman font.  This is a GNU extension.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -C     Recognize .EQ and .EN even when followed by  a  character  other
              than space or newline.

       -d xy  Specify  delimiters x for left and y for right ends of equations
              not bracketed by .EQ/.EN.  x and y need not  be  distinct.   Any
              “delim xy” statements in the source file override this option.

       -f F   is equivalent to “gfont F”.

       -m n   is equivalent to “set minimum_size n”.

       -M dir Search  dir  for  eqnrc before those listed in section “Descrip‐
              tion” above.

       -N     Prohibit newlines within delimiters.  This option allows eqn  to
              recover better from missing closing delimiters.

       -p n   Set  sub‐ and superscripts n points smaller than the surrounding
              text.  This option is deprecated.  eqn normally  sets  sub‐  and
              superscripts at 70% of the type size of the surrounding text.

       -r     Reduce  the type size of subscripts at most once relative to the
              base type size for the equation.

       -R     Don’t load eqnrc.

       -s n   is equivalent to “gsize n”.  This option is deprecated.

       -T dev Prepare output for the device dev.  In most cases, the effect of
              this is to define a macro dev with a value of 1; eqnrc uses this
              to provide definitions appropriate for the device.  However,  if
              the  specified  driver  is “MathML”, the output is MathML markup
              rather than troff input, and eqnrc is not loaded  at  all.   The
              default output device is ps.

Files
       /usr/share/groff/1.23.0/tmac/eqnrc
              Initialization file.

MathML mode limitations
       MathML  is  designed  on  the  assumption that it cannot know the exact
       physical characteristics of the media and devices on which it  will  be
       rendered.  It does not support control of motions and sizes to the same
       degree troff does.

       • eqn customization parameters have no effect on generated MathML.

       • The  special,  up,  down,  fwd,  and back primitives cannot be imple‐
         mented, and yield a MathML “<merror>” message instead.

       • The vcenter primitive is silently ignored, as centering on  the  math
         axis is the MathML default.

       • Characters  that eqn sets extra large in troff mode—notably the inte‐
         gral sign—may appear too small and  need  to  have  their  “<mstyle>”
         wrappers adjusted by hand.

       As  in its troff mode, eqn in MathML mode leaves the .EQ and .EN tokens
       in place, but emits nothing corresponding to  delim  delimiters.   They
       can,  however,  be  recognized  as  character sequences that begin with
       “<math>”, end with “</math>”, and do not cross line boundaries.

Caveats
       Tokens must be double‐quoted in eqn input if they are not to be  recog‐
       nized  as  names  of  macros or primitives, or if they are to be inter‐
       preted by troff.  In particular, short ones, like “pi”  and  “PI”,  can
       collide  with  troff identifiers.  For instance, the eqn command “gfont
       PI” does not select groff’s Palatino italic font for the global  italic
       face; you must use “gfont "PI"” instead.

       Delimited  equations  are set at the type size current at the beginning
       of the input line, not necessarily that immediately preceding the open‐
       ing delimiter.

       Unlike TeX, eqn does not inherently distinguish  displayed  and  inline
       equation  styles;  see  the  smallover primitive above.  However, macro
       packages frequently define EQ and EN  macros  such  that  the  equation
       within  is displayed.  These macros may accept arguments permitting the
       equation to be labeled or captioned; see the package’s documentation.

Bugs
       eqn abuses terminology—its “equations” can be  inequalities,  bare  ex‐
       pressions,  or  unintelligible  gibberish.   But there’s no changing it
       now.

       In nroff mode, lowercase Greek letters are rendered in roman instead of
       italic style.

       In MathML mode, the mark and lineup features don’t work.  These  could,
       in theory, be implemented with “<maligngroup>” elements.

       In  MathML  mode, each digit of a numeric literal gets a separate “<mn>
       </mn>” pair, and decimal points are tagged with “<mo></mo>”.   This  is
       allowed by the specification, but inefficient.

Examples
       We first illustrate eqn usage with a trigonometric identity.

              .EQ
              sin ( alpha + beta ) = sin alpha cos beta + cos alpha sin beta
              .EN

       It  can be convenient to set up delimiters if mathematical content will
       appear frequently in running text.

              .EQ
              delim $$
              .EN
              Having cached a table of logarithms,
              the property $ln ( x y ) = ln x + ln y$ sped calculations.

       The quadratic formula illustrates use of fractions  and  radicals,  and
       affords an opportunity to use the full space token ~.

              .EQ
              x = { - b ~ \[+-] ~ sqrt { b sup 2 - 4 a c } } over { 2 a }
              .EN

       Alternatively,  we  could define the plus‐minus sign as a binary opera‐
       tor.  Automatic spacing puts 0.06 em less space on either side  of  the
       plus‐minus than ~ does, this being the difference between the widths of
       the  medium_space  parameter  used  by binary operators and that of the
       full space.  Independently, we can define a macro  “frac”  for  setting
       fractions.

              .EQ
              chartype "binary" \[+-]
              define frac ! { $1 } over { $2 } !
              x = frac(- b \[+-] sqrt { b sup 2 - 4 a c }, 2 a)
              .EN

See also
       “Typesetting  Mathematics—User’s  Guide”  (2nd  edition),  by  Brian W.
       Kernighan and Lorinda L. Cherry, 1978, AT&T Bell Laboratories Computing
       Science Technical Report No. 17.

       The TeXbook, by Donald E.  Knuth,  1984,  Addison‐Wesley  Professional.
       Appendix  G  discusses  many of the parameters from section “Customiza‐
       tion” above in greater detail.

       groff_char(7), particularly subsections “Logical symbols”,  “Mathemati‐
       cal  symbols”, and “Greek glyphs”, documents a variety of special char‐
       acter escape sequences useful in mathematical typesetting.

       groff(1), troff(1), pic(1), groff_font(5)

groff 1.23.0                      2 July 2023                           eqn(1)
───────────────────────────────────────────────────────────────────────────────
eqn2graph(1)                General Commands Manual               eqn2graph(1)

Name
       eqn2graph - convert an eqn equation into a cropped image

Synopsis
       eqn2graph [-format output‐format] [convert‐argument ...]

       eqn2graph --help

       eqn2graph -v
       eqn2graph --version

Description
       eqn2graph reads a one‐line eqn(1) equation from the standard input  and
       writes  an  image  file,  by default in Portable Network Graphics (PNG)
       format, to the standard output.

       The input EQN code should not be preceded by the .EQ  macro  that  nor‐
       mally  precedes it within groff(1) macros; nor do you need to have dol‐
       lar‐sign or other delimiters around the equation.

       Arguments not recognized by eqn2graph are passed to the ImageMagick  or
       GraphicsMagick  program  convert(1).  By specifying these, you can give
       your image a border, set the image’s pixel density,  or  perform  other
       useful transformations.

       The  output image is clipped using convert’s -trim option to the small‐
       est possible bounding box that contains all the black pixels.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -format output‐format
              Write  the  image  in output‐format, which must be understood by
              convert; the default is PNG.

Environment
       GROFF_TMPDIR
       TMPDIR
       TMP
       TEMP   These environment variables are searched in the given  order  to
              determine  the  directory where temporary files will be created.
              If none are set, /tmp is used.

Authors
       eqn2graph was written by Eric S. Raymond ⟨esr@thyrsus.com⟩, based on  a
       recipe for pic2graph(1), by W. Richard Stevens.

See also
       pic2graph(1), grap2graph(1), eqn(1), groff(1), convert(1)

groff 1.23.0                      2 July 2023                     eqn2graph(1)
───────────────────────────────────────────────────────────────────────────────
gdiffmk(1)                  General Commands Manual                 gdiffmk(1)

Name
       gdiffmk - mark differences between groff/nroff/troff files

Synopsis
       gdiffmk [-a add‐mark] [-c change‐mark] [-d delete‐mark] [-x diff‐
               command] [-D [-B] [-M mark1 mark2]] [--] file1 file2 [output]

       gdiffmk --help

       gdiffmk --version

Description
       gdiffmk  compares two roff(7) documents, file1 and file2, and creates a
       roff document consisting of file2 with added margin character (.mc) re‐
       quests indicating output lines that differ from file1.  If the file1 or
       file2 argument is “-”, gdiffmk reads the standard input stream for that
       input.  If the output operand is present, gdiffmk writes  output  to  a
       file  of  that  name.  If it is “-” or absent, gdiffmk writes output to
       the standard output stream.  “-” cannot be both  an  input  and  output
       operand.

Options
       --help  displays  a  usage message and --version shows version informa‐
       tion; both exit afterward.

       -a add‐mark
              Use add‐mark for source lines not in file1 but present in file2.
              Default: “+”.

       -B     By default, the deleted texts marked by the -D option  end  with
              an  added  roff break request, .br, to ensure that the deletions
              are marked properly.  This is the only  way  to  guarantee  that
              deletions  and  small  changes get flagged.  This option directs
              the program not to insert these breaks; it makes no sense to use
              it without -D.

       -c change‐mark
              Use change‐mark for changed source lines.  Default: “|”.

       -d delete‐mark
              Use the delete‐mark for deleted source lines.  Default: “*”.

       -D     Show the deleted portions from changed and deleted text.

       -M mark1 mark2
              Change the delimiting marks for the  -D  option.   It  makes  no
              sense  to use this option without -D.  Default delimiting marks:
              “[[” ... “]]”.

       -x diff‐command
              Use the diff‐command command to perform the comparison of  file1
              and  file2.   In  particular, diff‐command should accept the GNU
              diff(1) -D option.  Default: diff.

       --     Treat all subsequent arguments as file names, even if they begin
              with “-”.

Bugs
       The output is not necessarily compatible with all  macro  packages  and
       all  preprocessors.   A  workaround  that  often overcomes preprocessor
       problems is to run gdiffmk on the output of all the  preprocessors  in‐
       stead of the input source.

       gdiffmk  relies  on the -D option of GNU diff to make a merged “#ifdef”
       output format.  Busybox diff is known to not support it.  Also see  the
       -x diff‐command option.

Authors
       gdiffmk was written by Mike Bianchi ⟨MBianchi@Foveal.com⟩, now retired.
       It is maintained by the groff developers.

See also
       groff(1), nroff(1), gtroff(1), roff(7), diff(1)

groff 1.23.0                      2 July 2023                       gdiffmk(1)
───────────────────────────────────────────────────────────────────────────────
glilypond(1)                General Commands Manual               glilypond(1)

Name
       glilypond - embed LilyPond musical notation in groff documents

Synopsis
       glilypond [-k] [{--ly2eps|--pdf2eps}] [-e directory] [-o output‐file]
                 [-p filename‐prefix] [-t tdir] [{-v|-V}] [--] [file ...]
       glilypond [{--ly2eps|--pdf2eps}] [--eps_dir directory] [--keep_all]
                 [--output output‐file] [--prefix filename‐prefix] [--temp_dir
                 tdir] [--verbose] [--] [file ...]

       glilypond -?
       glilypond -h
       glilypond --help
       glilypond --usage

       glilypond -l
       glilypond --license

       glilypond --version

Description
       glilypond  is  a  groff(7)  preprocessor  that enables the embedding of
       LilyPond music scores in groff documents.  If no operands are given, or
       if file is “-”, glilypond reads the standard input stream.   A  double‐
       dash  argument (“--”) causes all subsequent arguments to be interpreted
       as file operands, even if their names start with a dash.

Usage
       At present, glilypond works with the groff ps, dvi, html, and xhtml de‐
       vices.  The lbp and lj4 devices are untested.  Unfortunately,  the  pdf
       device does not yet work.

Option overview
       -?|-h|--help|--usage
              Display usage information and exit.

       --version
              Display version information and exit.

       -l|--license
              Display copyright license information and exit.

   Options for building EPS files
       --ly2eps
              Direct  lilypond(1)  to  create  Encapsulated  PostScript  (EPS)
              files.  This is the default.

       --pdf2eps
              The program glilypond generates a PDF file using lilypond.  Then
              the EPS file is generated by pdf2ps and ps2eps.

   Directories and files
       -e|--eps_dir directory_name
              Normally all EPS files are  sent  to  the  temporary  directory.
              With  this option, you can generate your own directory, in which
              all useful EPS files are send.  So at last, the temporary direc‐
              tory can be removed.

       -p|--prefix begin_of_name
              Normally all temporary files get names that start with the ly...
              prefix.  With this option, you can freely change this prefix.

       -k|--keep_all
              Normally all temporary files without the eps files are  deleted.
              With  this  option,  all  generated files either by the lilypond
              program or other format transposers are kept.

       -t|--temp_dir dir
              With this option, you call a directory that is the base for  the
              temporary  directory.  This directory name is used as is without
              any extensions.  If this directory does not exist it is be  cre‐
              ated.  The temporary directory is created by Perl’s security op‐
              erations  directly  under this directory.  In this temporary di‐
              rectory, the temporary files are stored.

   Output
       -o|--output file_name
              Normally all groff output of this program  is  sent  to  STDOUT.
              With  this  option, that can be changed, such that the output is
              stored into a file named in the option argument file_name.

       -v|-V|--verbose
              A lot more of information is sent to STDERR.

   Short option collections
       The argument handling of options

       Short options are arguments that start with a single dash -.   Such  an
       argument can consist of arbitrary many options without option argument,
       composed  as  a  collection  of  option characters following the single
       dash.

       Such a collection can be terminated by an option character that expects
       an option argument.  If this option character is not the last character
       of the argument, the following final part of the argument is the option
       argument.  If it is the last character of the argument, the next  argu‐
       ment is taken as the option argument.

       This is the standard for POSIX and GNU option management.

       For example,

       -kVe some_dir
              is  a  collection  of the short options -k and -V without option
              argument, followed by the short option -e with  option  argument
              that  is  the  following part of the argument some_dir.  So this
              argument could also be written as several  arguments  -k  -V  -e
              some_dir.

   Handling of long options
       Arguments that start with a double dash -- are so‐called long options R
       .  Each double dash argument can only have a single long option.

       Long  options  have or have not an option argument.  An option argument
       can be the next argument or can be appended with an equal sign = to the
       same argument as the long option.

       --help is a long option without an option argument.

       --eps_dir some_dir
       --eps_dir=some_dir
              is the long option --eps_dir with the option argument some_dir.

       Moreover the program allows abbreviations of long options, as  much  as
       possible.

       The  long option --keep_all can be abbreviated from --keep_al up to --k
       because the program does not have another long option whose name starts
       with the character k.

       On the other hand, the option --version cannot be  abbreviated  further
       than --vers because there is also the long option --verbose that can be
       abbreviated up to --verb.

       An  option  argument  can  also  be appended to an abbreviation.  So is
       --e=some_dir the same as --eps_dir some_dir.

       Moreover the program allows an arbitrary usage of upper and lower  case
       in the option name.  This is Perl style.

       For  example,  the  long  option  --keep_all  can as well be written as
       --Keep_All or even as an abbreviation like --KeE.

LilyPond regions in roff input
   Integrated LilyPond code
       A lilypond part within a structure written in the groff language is the
       whole part between the marks
              .lilypond start
       and
              .lilypond end
       A groff input can have several of these lilypond parts.

       When processing such a lilypond part between .lilypond start and .lily‐
       pond end we say that the glilypond program is in lilypond mode.

       These lilypond parts are sent into temporary lilypond  files  with  the
       file name extension .ly.  These files are transformed later on into EPS
       files.

   Inclusion of .ly files
       An  additional  command  line  for  file inclusion of lilypond files is
       given by
       .lilypond include file_name
       in groff input.  For each such include command, one  file  of  lilypond
       code  can  be  included into the groff code.  Arbitrarily many of these
       commands can be included in the groff input.

       These include commands can only be used  outside  the  lilypond  parts.
       Within the lilypond mode, this inclusion is not possible.  So .lilypond
       include  may not be used in lilypond mode, i.e. between .lilypond start
       and .lilypond end.  These included ly‐files are also  transformed  into
       EPS files.

Generated files
       By  the  transformation process of lilypond parts into EPS files, there
       are many files generated.  By default, these files are regarded as tem‐
       porary files and as such stored in a temporary directory.

       This process can be changed by command‐line options.

   Command‐line options for directories
       The temporary directory for this program is  either  created  automati‐
       cally or can be named by the option -t|--temp_dir dir.

       Moreover, the EPS files that are later on referred by .PSPIC command in
       the  final groff output can be stored in a different directory that can
       be set by the command‐line option  -e|--eps_dir  directory_name.   With
       this  option,  the temporary directory can be removed completely at the
       end of the program.

       The beginning of the names of the temporary files can  be  set  by  the
       command‐line options -p or --prefix.

       All  of  the  temporary files except the EPS files are deleted finally.
       This  can  be  changed  by  setting  the  command‐line  options  -k  or
       --keep_files.  With this, all temporary files and directories are kept,
       not deleted.

       These  EPS  files are stored in a temporary or EPS directory.  But they
       cannot be deleted by the transformation process because they are needed
       for the display which can take a long time.

Transformation processes for generating EPS files
   Mode pdf2eps
       This mode is the actual default and can also be chosen  by  the  option
       --pdf2eps.

       In  this mode, the .ly files are transformed by the lilypond(1) program
       into PDF files, using
              lilypond --pdf --output=file‐name
       for each .ly file.  The file‐name must be provided without  the  exten‐
       sion .pdf.  By this process, a file file‐name.pdf is generated.

       The  next step is to transform these PDF files into a PS file.  This is
       done by the pdf2ps(1) program using
              $ pdf2ps file‐name.pdf file‐name.pds
       The next step creates an EPS file from the PS file.  This  is  done  by
       the ps2eps(1) program using
              $ ps2eps file‐name.ps

       By  that, a file file‐name.eps is created for each lilypond part in the
       groff file or standard input.

       The last step to be done is replacing all lilypond parts by  the  groff
       command
              .PSPIC file‐name.eps

   Mode ly2eps
       In  earlier  time, this mode was the default.  But now it does not work
       any more, so accept the new default pdf2eps.  For  testing,  this  mode
       can also be chosen by the glilypond option --ly2eps.

       In  this  mode,  the  .ly files are transformed by the lilypond program
       into many files of different formats, including eps files, using
              $ lilypond --ps -dbackend=eps -dgs-load-fonts --output=file‐name
       for each .ly file.  The output file-name must be  provided  without  an
       extension, its directory is temporary.

       There  are many EPS files created.  One having the complete transformed
       ly file, named file-name.eps.

       Moreover there are EPS files for each page, named file-name-digit.eps.

       The last step to be done is replacing all lilypond parts by the collec‐
       tion of the corresponding EPS page files.  This is done by  groff  com‐
       mands
       .PSPIC file‐name-digit.eps

Generated groff output
       The new groff(7) structure generated by glilypond is either

       1)     sent  to  standard  output and can there be saved into a file or
              piped into groff(1) or

       2)     stored into a file by given the option -o  | --output file_name

Authors
       glilypond was written by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.

See also
       groff(1)
              describes the usage of the groff command and  contains  pointers
              to further documentation of the groff system.

       groff_tmac(5)
              describes the .PSPIC request.

       lilypond(1)
              briefly  describes the lilypond command and contains pointers to
              further documentation.

       pdf2ps(1)
              transforms a PDF file into a PostScript format.

       ps2eps(1)
              transforms a PS file into an EPS format.

groff 1.23.0                      2 July 2023                     glilypond(1)
───────────────────────────────────────────────────────────────────────────────
gperl(1)                    General Commands Manual                   gperl(1)

Name
       gperl - execute Perl commands in groff documents

Synopsis
       gperl [file ...]

       gperl -h
       gperl --help

       gperl -v
       gperl --version

Description
       This is a preprocessor for groff(1).  It allows the use of perl(7) code
       in groff(7) files.  The result of a Perl part can be  stored  in  groff
       strings  or  numerical registers based on the arguments at a final line
       of a Perl part.

       If no operands are given, or if file is “-”, gperl reads  the  standard
       input  stream.  A double‐dash argument (“--”) causes all subsequent ar‐
       guments to be interpreted as file operands, even if their  names  start
       with  a  dash.   -h  and --help display a usage message, whereas -v and
       --version display version information; all exit afterward.

Perl regions
       Perl parts in groff files are enclosed by two .Perl requests with  dif‐
       ferent arguments, a starting and an ending command.

   Starting Perl mode
       The  starting Perl request can either be without arguments, or by a re‐
       quest that has the term start as its only argument.

              •      .Perl

              •      .Perl start

   Ending Perl mode without storage
       A .Perl command line with an argument different from start  finishes  a
       running  Perl part.  Of course, it would be reasonable to add the argu‐
       ment stop; that’s possible, but not necessary.

              •      .Perl stop

              •      .Perl other_than_start
       The argument other_than_start can  additionally  be  used  as  a  groff
       string variable name for storage — see next section.

   Ending Perl mode with storage
       A useful feature of gperl is to store one or more results from the Perl
       mode.

       The output of a Perl part can be got with backticks `...`.

       This  program  collects all printing to STDOUT (normal standard output)
       by the Perl print program.  This pseudo‐printing output can  have  sev‐
       eral lines, due to printed line breaks with \n.  By that, the output of
       a  Perl  run should be stored into a Perl array, with a single line for
       each array member.

       This Perl array output can be stored by gperl in either

       groff strings
              by creating a groff command .ds

       groff register
              by creating a groff command .rn

       The storage modes can be determined by arguments of  a  final  stopping
       .Perl  command.   Each  argument .ds changes the mode into groff string
       and .nr changes the mode into groff register for all  following  output
       parts.

       By default, all output is saved as strings, so .ds is not really needed
       before  the  first  .nr command.  That suits to groff(7), because every
       output can be saved as groff string, but the registers can be very  re‐
       strictive.

       In string mode, gperl generates a groff string storage line
              .ds var_name content
       In register mode the following groff command is generated
              .nr var_name content

       We present argument collections in the following.  You can add as first
       argument for all stop.  We omit this additional element.

       .Perl .ds var_name
              This  will  store  1  output  line  into  the groff string named
              var_name by the automatically created command
                     .ds var_name output

       .Perl var_name
              If var_name is different from start this is  equivalent  to  the
              former  command, because the string mode is string with .ds com‐
              mand.  default.

       .Perl var_name1 var_name2
              This will store 2 output lines into groff string names var_name1
              and var_name2, because the default mode .ds is active, such that
              no .ds argument is needed.  Of course, this is equivalent to
                     .Perl .ds var_name1 var_name2
              and
                     .Perl .ds var_name1 .ds var_name2

       .Perl .nr var_name1 varname2
              stores both variables as register variables.  gperl generates
              .nr var_name1 output_line1
              .nr var_name2 output_line2

       .Perl .nr var_name1 .ds var_name2
              stores the 1st argument as register and the second as string by
              .nr var_name1 output_line1
              .ds var_name2 output_line2

Example
       A possible Perl part in a roff file could look like that:
              before
              .Perl start
              my $result = 'some data';
              print $result;
              .Perl stop .ds string_var
              after

       This stores  the  result  ”some  data”  into  the  roff  string  called
       string_var, such that the following line is printed:
              .ds string_var some data
       by gperl as food for the coming groff run.

       A Perl part with several outputs is:
              .Perl start
              print ”first\n”;
              print ”second line\n”;
              print ”3\n”;
              .Perl var1 var2 .nr var3
       This  stores 3 printed lines into 3 groff strings.  var1,var2,var3.  So
       the following groff command lines are created:
              .ds var1 first
              .ds var2 second line
              .nr var3 3

Authors
       gperl was written by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.

See also
       Man pages related to groff are groff(1), groff(7), and grog(1).

       Documents related to Perl are perl(1), perl(7).

groff 1.23.0                      2 July 2023                         gperl(1)
───────────────────────────────────────────────────────────────────────────────
gpinyin(1)                  General Commands Manual                 gpinyin(1)

Name
       gpinyin - use Hanyu Pinyin Chinese in groff documents

Synopsis
       gpinyin [file ...]

       gpinyin -h
       gpinyin --help

       gpinyin -v
       gpinyin --version

Description
       gpinyin is a preprocessor for groff(1) that facilitates  use  of  Hanyu
       Pinyin  in groff(7) files.  Pinyin is a method for writing the Mandarin
       Chinese language with the Latin alphabet.  Mandarin  consists  of  more
       than  four hundred base syllables, each spoken with one of five differ‐
       ent tones.  Changing the tone applied to the syllable generally  alters
       the  meaning of the word it forms.  In Pinyin, a syllable is written in
       the Latin alphabet and a numeric tone indicator can be appended to each
       syllable.

       Each input‐file is a file name or the character “-”  to  indicate  that
       the  standard input stream should be read.  As usual, the argument “--”
       can be used in order to force interpretation of all remaining arguments
       as file names, even if an input‐file argument begins with  a  “-”.   -h
       and --help display a usage message, while -v and --version show version
       information; all exit afterward.

   Pinyin sections
       Pinyin  sections  in  groff  files are enclosed by two .pinyin requests
       with different arguments.  The starting request is
              .pinyin start
       or
              .pinyin begin
       and the ending request is
              .pinyin stop
       or
              .pinyin end
       .

   Syllables
       In Pinyin, each syllable is represented by one  to  six  letters  drawn
       from  the  fifty‐two  upper‐ and lowercase letters of the Unicode basic
       Latin character set, plus the letter “U” with dieresis (umlaut) in both
       cases—in other words, the members of the set “[a–zA–ZüÜ]”.

       In groff input, all basic Latin letters are written as themselves.  The
       “u with dieresis” can be written as “\[:u]” in lowercase or “\[:U]”  in
       uppercase.  Within .pinyin sections, gpinyin supports the form “ue” for
       lowercase and the forms “Ue” and “UE” for uppercase.

   Tones
       Each syllable has exactly one of five tones.  The fifth tone is not ex‐
       plicitly  written at all, but each of the first through fourth tones is
       indicated with a diacritic above a specific vowel within the syllable.

       In a gpinyin source file, these tones are written by adding  a  numeral
       in  the  range  0 to 5 after the syllable.  The tone numbers 1 to 4 are
       transformed into accents above vowels in the output.  The tone  numbers
       0 and 5 are synonymous.

       The tones are written as follows.

       Tone     Description      Diacritic   Example Input   Example Output
       ─────────────────────────────────────────────────────────────────────
       first    flat             ¯           ma1             mā
       second   rising           ´           ma2             má
       third    falling‐rising   ˇ           ma3             mǎ
       fourth   falling          `           ma4             mà
       fifth    neutral          (none)      ma0             ma
                                             ma5

       The  neutral tone number can be omitted from a word‐final syllable, but
       not otherwise.

Authors
       gpinyin was written by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.

See also
       Useful documents on the World Wide Web related to Pinyin include
           Pinyin to Unicode ⟨http://www.foolsworkshop.com/ptou/index.html⟩,
           On‐line Chinese Tools ⟨http://www.mandarintools.com/⟩,
           Pinyin.info: a guide to the writing of Mandarin Chinese in roman‐
           ization ⟨http://www.pinyin.info/index.html⟩,
           “Where  do  the  tone  marks  go?”   ⟨http://www.pinyin.info/rules/
           where.html⟩,
           pinyin.txt  from the CJK macro package for TeX ⟨http://git.savannah
           .gnu.org/gitweb/?p=cjk.git;a=blob_plain;f=doc/pinyin.txt;hb=HEAD⟩,
       and
           pinyin.sty from the CJK macro package for TeX ⟨http://git.savannah
           .gnu.org/gitweb/?p=cjk.git;a=blob_plain;f=texinput/pinyin.sty
           ;hb=HEAD⟩.

       groff(1) and grog(1) explain how to view roff documents.

       groff(7) and groff_char(7) are comprehensive  references  covering  the
       language  elements of GNU troff and the available glyph repertoire, re‐
       spectively.

groff 1.23.0                      2 July 2023                       gpinyin(1)
───────────────────────────────────────────────────────────────────────────────
grap2graph(1)               General Commands Manual              grap2graph(1)

Name
       grap2graph - convert a grap diagram into a cropped image

Synopsis
       grap2graph [-unsafe] [-format output‐format] [convert‐argument ...]

       grap2graph --help

       grap2graph -v
       grap2graph --version

Description
       grap2graph reads a grap(1) program from the standard input  and  writes
       an image file, by default in Portable Network Graphics (PNG) format, to
       the standard output.

       The  input  GRAP code should not be wrapped with the .G1 and .G2 macros
       that normally guard it within groff(1) documents.

       Arguments not recognized by grap2graph are passed to the ImageMagick or
       GraphicsMagick program convert(1).  By specifying these, you  can  give
       your  image  a  border, set the image’s pixel density, or perform other
       useful transformations.

       The output image is clipped using convert’s -trim option to the  small‐
       est possible bounding box that contains all the black pixels.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -format output‐format
              Write the image in output‐format, which must  be  understood  by
              convert; the default is PNG.

       -unsafe
              Run groff in unsafe mode, enabling the PIC command sh to execute
              arbitrary  Unix  shell commands.  The groff default is to forbid
              this.

Environment
       GROFF_TMPDIR
       TMPDIR
       TMP
       TEMP   These environment variables are searched in the given  order  to
              determine  the  directory where temporary files will be created.
              If none are set, /tmp is used.

Authors
       grap2graph was written by Eric S. Raymond ⟨esr@thyrsus.com⟩, based on a
       recipe for pic2graph(1), by W. Richard Stevens.

See also
       pic2graph(1), eqn2graph(1), grap(1), pic(1), groff(1), convert(1)

groff 1.23.0                      2 July 2023                    grap2graph(1)
───────────────────────────────────────────────────────────────────────────────
grn(1)                      General Commands Manual                     grn(1)

Name
       grn - embed Gremlin images in groff documents

Synopsis
       grn [-C] [-T dev] [-M dir] [-F dir] [file ...]

       grn -?
       grn --help

       grn -v
       grn --version

Description
       grn is a preprocessor for including gremlin pictures in troff(1) input.
       grn writes to standard output, processing only input lines between  two
       that  start  with  .GS  and .GE.  Those lines must contain grn commands
       (see below).  These macros request a gremlin file; the picture in  that
       file  is  converted  and  placed in the troff input stream.  .GS may be
       called with a C, L, or R argument to center,  left‐,  or  right‐justify
       the  whole  gremlin  picture (the default is to center).  If no file is
       mentioned, the standard input is read.  At the end of the picture,  the
       position  on the page is the bottom of the gremlin picture.  If the grn
       entry is ended with .GF instead of .GE, the position is left at the top
       of the picture.

       Currently only the me macro package has support for .GS, .GE, and .GF.

       grn produces drawing escape sequences that use groff’s color scheme ex‐
       tension (\D'F ...'), and thus may not work with other troffs.

   grn commands
       Each input line between .GS and .GE may have one grn command.  Commands
       consist of one or two strings  separated  by  white  space,  the  first
       string  being  the command and the second its operand.  Commands may be
       upper‐ or lowercase and abbreviated down to one character.

       Commands that affect  a  picture’s  environment  (those  listed  before
       “default”,  see  below) are only in effect for the current picture: the
       environment is reinitialized to the defaults at the start of  the  next
       picture.  The commands are as follows.

       1 N
       2 N
       3 N
       4 N    Set  gremlin’s text size number 1 (2, 3, or 4) to N points.  The
              default is 12 (16, 24, and 36, respectively).

       roman f
       italics f
       bold f
       special f
              Set the roman (italics, bold, or special) font to troff’s font f
              (either a name or number).  The default is R (I, B, and  S,  re‐
              spectively).

       l f
       stipple f
              Set the stipple font to troff’s stipple font f (name or number).
              The  command  stipple may be abbreviated down as far as “st” (to
              avoid confusion with “special”).  There is no default for  stip‐
              ples (unless one is set by the “default” command), and it is in‐
              valid  to include a gremlin picture with polygons without speci‐
              fying a stipple font.

       x N
       scale N
              Magnify the picture (in addition to any  default  magnification)
              by  N,  a  floating‐point  number larger than zero.  The command
              scale may be abbreviated down to “sc”.

       narrow N
       medium N
       thick N
              Set the thickness of gremlin’s narrow (medium and thick, respec‐
              tively) lines to N times 0.15pt (this value can  be  changed  at
              compile  time).  The default is 1.0 (3.0 and 5.0, respectively),
              which corresponds to 0.15pt (0.45pt and  0.75pt,  respectively).
              A  thickness  value  of zero selects the smallest available line
              thickness.  Negative values cause the line thickness to be  pro‐
              portional to the current point size.

       pointscale [off|on]
              Scale  text  to  match  the  picture.   Gremlin  text is usually
              printed in the point size specified with the commands 1,  2,  3,
              or 4, regardless of any scaling factors in the picture.  Setting
              pointscale  will cause the point sizes to scale with the picture
              (within troff’s limitations, of course).  An operand of anything
              but off will turn text scaling on.

       default
              Reset the picture environment defaults to the  settings  in  the
              current picture.  This is meant to be used as a global parameter
              setting  mechanism at the beginning of the troff input file, but
              can be used at any time to reset the default settings.

       width N
              Force the picture to be N inches wide.  This overrides any scal‐
              ing factors present in the same picture.  “width 0” is ignored.

       height N
              Force the picture to be N inches high, overriding other  scaling
              factors.   If  both  width and height are specified, the tighter
              constraint will determine the scale of the picture.  height  and
              width  commands  are  not  saved with a “default” command.  They
              will, however, affect point size scaling if that option is set.

       file name
              Get picture from gremlin file name located the current directory
              (or in the library directory; see the -M option above).  If mul‐
              tiple file commands are given, the last one controls.   If  name
              doesn’t  exist, an error message is reported and processing con‐
              tinues from the .GE line.

   Usage with groff
       Since grn is a preprocessor, it has no access to elements of  formatter
       state, such as indentation, line length, type size, or register values.
       Consequently,  no  troff  input  can  be placed between the .GS and .GE
       macros.  However, gremlin text elements are subsequently  processed  by
       troff,  so anything valid in a single line of troff input is valid in a
       line of gremlin text (barring the dot control character “.” at the  be‐
       ginning  of  a  line).  Thus, it is possible to have equations within a
       gremlin figure by including in the gremlin  file  eqn  expressions  en‐
       closed by previously defined delimiters (e.g., “$$”).

       When using grn along with other preprocessors, it is best to run tbl(1)
       before  grn,  pic(1),  and/or  ideal  to avoid overworking tbl.  eqn(1)
       should always be run last.  groff(1) will automatically run  preproces‐
       sors in the correct order.

       A  picture  is  considered  an entity, but that doesn’t stop troff from
       trying to break it up if it falls off the end of a page.   Placing  the
       picture between “keeps” in the me macros will ensure proper placement.

       grn  uses  troff’s registers g1 through g9 and sets registers g1 and g2
       to the width and height of the gremlin figure (in device units)  before
       entering  the  .GS  macro  (this is for those who want to rewrite these
       macros).

   Gremlin file format
       There exist two distinct gremlin file formats: the original format  for
       AED  graphic  terminals, and the Sun or X11 version.  An extension used
       by the Sun/X11 version allowing reference points with negative  coordi‐
       nates  is  not  compatible  with the AED version.  As long as a gremlin
       file does not contain negative coordinates, either format will be  read
       correctly by either version of gremlin or grn.  The other difference in
       Sun/X11  format is the use of names for picture objects (e.g., POLYGON,
       CURVE) instead of numbers.  Files representing  the  same  picture  are
       shown below.

                        sungremlinfile        gremlinfile
                        0 240.00 128.00       0 240.00 128.00
                        CENTCENT              2
                        240.00 128.00         240.00 128.00
                        185.00 120.00         185.00 120.00
                        240.00 120.00         240.00 120.00
                        296.00 120.00         296.00 120.00
                        *                     -1.00 -1.00
                        2 3                   2 3
                        10 A Triangle         10 A Triangle
                        POLYGON               6
                        224.00 416.00         224.00 416.00
                        96.00 160.00          96.00 160.00
                        384.00 160.00         384.00 160.00
                        *                     -1.00 -1.00
                        5 1                   5 1
                        0                     0
                        -1                    -1

       • The first line of each gremlin file contains either the string “grem‐
         linfile” (AED) or “sungremlinfile” (Sun/X11).

       • The  second line of the file contains an orientation and x and y val‐
         ues for a positioning point, separated by spaces.   The  orientation,
         either 0 or 1, is ignored by the Sun/X11 version.  0 means that grem‐
         lin  will  display  things in horizontal format (a drawing area wider
         than it is tall, with a menu across the top).  1 means  that  gremlin
         will display things in vertical format (a drawing area taller than it
         is  wide,  with a menu on the left side).  x and y are floating‐point
         values giving a positioning point to be used when this file  is  read
         into  another file.  The stuff on this line really isn’t all that im‐
         portant; a value of “1 0.00 0.00” is suggested.

       • The rest of the file consists of zero or more element specifications.
         After the last element specification is a line containing the  string
         “-1”.

       • Lines longer than 127 characters are truncated to that length.

   Element specifications
       • The  first line of each element contains a single decimal number giv‐
         ing the type of the element (AED) or its name (Sun/X11).

                    gremlin File Format: Object Type Specification
               ─────────────────────────────────────────────────────────
               AED Number   Sun/X11 Name           Description
                    0       BOTLEFT        bottom‐left‐justified text
                    1       BOTRIGHT       bottom‐right‐justified text
                    2       CENTCENT       center‐justified text
                    3       VECTOR         vector
                    4       ARC            arc
                    5       CURVE          curve
                    6       POLYGON        polygon
                    7       BSPLINE        b‐spline
                    8       BEZIER         Bézier
                   10       TOPLEFT        top‐left‐justified text
                   11       TOPCENT        top‐center‐justified text
                   12       TOPRIGHT       top‐right‐justified text
                   13       CENTLEFT       left‐center‐justified text
                   14       CENTRIGHT      right‐center‐justified text
                   15       BOTCENT        bottom‐center‐justified text

       • After the object type comes a variable number of lines, each specify‐
         ing a point used to display the element.  Each line contains an x‐co‐
         ordinate and a y‐coordinate in floating‐point  format,  separated  by
         spaces.   The  list  of points is terminated by a line containing the
         string “-1.0 -1.0” (AED) or a single asterisk, “*” (Sun/X11).

       • After the points comes a line containing two decimal  values,  giving
         the  brush  and size for the element.  The brush determines the style
         in which things are drawn.  For vectors, arcs, and curves  there  are
         six valid brush values.

                               1   thin dotted lines
                               2   thin dot‐dashed lines
                               3   thick solid lines
                               4   thin dashed lines
                               5   thin solid lines
                               6   medium solid lines

         For  polygons,  one  more value, 0, is valid.  It specifies a polygon
         with an invisible border.  For text, the brush selects a font as fol‐
         lows.

                             1   roman (R font in troff)
                             2   italics (I font in troff)
                             3   bold (B font in troff)
                             4   special (S font in troff)

         If you’re using grn to run your pictures through groff, the  font  is
         really  just a starting font.  The text string can contain formatting
         sequences like “\fI” or “\d” which may change the font (as well as do
         many other things).  For text, the size field is a decimal value  be‐
         tween  1  and  4.   It selects the size of the font in which the text
         will be drawn.  For polygons, this size field  is  interpreted  as  a
         stipple number to fill the polygon with.  The number is used to index
         into a stipple font at print time.

       • The  last line of each element contains a decimal number and a string
         of characters, separated by a single space.  The number is a count of
         the number of characters in the string.   This  information  is  used
         only  for  text elements, and contains the text string.  There can be
         spaces inside the text.  For arcs, curves, and vectors, the character
         count is zero (0), followed by exactly one space before the newline.

   Coordinates
       gremlin was designed for AED terminals, and its coordinates reflect the
       AED coordinate space.  For vertical pictures, x  values  range  116  to
       511,  and  y  values  from 0 to 483.  For horizontal pictures, x values
       range from 0 to 511, and y values from 0 to 367.  Although you  needn’t
       absolutely  stick  to  this  range, you’ll get better results if you at
       least stay in this vicinity.  Also, point lists  are  terminated  by  a
       point  of  (-1,  -1),  so  you shouldn’t ever use negative coordinates.
       gremlin writes out coordinates using the printf(3) format “%f1.2”; it’s
       probably a good idea to use the same format if you want to  modify  the
       grn code.

   Sun/X11 coordinates
       There  is no restriction on the range of coordinates used to create ob‐
       jects in the Sun/X11 version of gremlin.  However, files with  negative
       coordinates will cause problems if displayed on the AED.

Options
       -? and --help display a usage message, while -v and --version show ver‐
       sion information; all exit afterward.

       -C     Recognize  .GS and .GE (and .GF) even when followed by a charac‐
              ter other than space or newline.

       -F dir Search dir for subdirectories devname (name is the name  of  the
              output  driver) for the DESC file before the default font direc‐
              tories /usr/share/groff/site-font, /usr/share/groff/1.23.0/font,
              and /usr/lib/font.

       -M dir Prepend dir to the search path for gremlin files.   The  default
              search  path is the current directory, the home directory, /usr/
              share/groff/site-tmac, and /usr/share/groff/1.23.0/tmac, in that
              order.

       -T dev Prepare device output using output driver dev.  The  default  is
              ps.  See groff(1) for a list of valid devices.

Files
       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

Authors
       David  Slattengren  and Barry Roitblat wrote the original Berkeley grn.
       Daniel Senderowicz and Werner Lemberg modified it for groff.

See also
       gremlin(1), groff(1), pic(1), ideal(1)

groff 1.23.0                      2 July 2023                           grn(1)
───────────────────────────────────────────────────────────────────────────────
grodvi(1)                   General Commands Manual                  grodvi(1)

Name
       grodvi - groff output driver for TeX DVI format

Synopsis
       grodvi [-dl] [-F dir] [-p paper‐format] [-w n] [file ...]

       grodvi --help

       grodvi -v
       grodvi --version

Description
       The GNU roff DVI output driver translates the output of  troff(1)  into
       TeX  DVI format.  Normally, grodvi is invoked by groff(1) when the lat‐
       ter is given the “-T dvi” option.  (In this installation, ps is the de‐
       fault output device.)  Use groff’s -P option to pass any options  shown
       above  to  grodvi.   If no file arguments are given, or if file is “-”,
       grodvi reads the standard input stream.  Output is written to the stan‐
       dard output stream.

       The DVI file generated by grodvi can interpreted by any correctly writ‐
       ten DVI driver.  troff drawing primitives are  implemented  using  tpic
       version  2  specials.   If the driver does not support these, \D escape
       sequences will not produce any output.

       Encapsulated PostScript (EPS) files can be  easily  included;  use  the
       PSPIC  macro.   pspic.tmac  is  loaded  automatically by dvi.tmac.  See
       groff_tmac(5).

       The default color used by the \m and  \M  escape  sequences  is  black.
       Currently,  the  stroke color for \D drawing escape sequences is black;
       fill color values are translated to gray.

       In groff, as in AT&T troff, the \N escape sequence can be used  to  ac‐
       cess any glyph in the current font by its position in the corresponding
       TFM file.

       By design, the DVI format doesn’t care about the physical dimensions of
       the  output  medium.   Instead,  grodvi  emits  the equivalent to TeX’s
       \special{papersize=width,length} on the first page; dvips  (or  another
       DVI  driver)  then  sets the page size accordingly.  If either the page
       width or length is not positive, no papersize special is output.

       A device control escape sequence \X'anything' is translated to the same
       DVI file instructions as would be  produced  by  \special{anything}  in
       TeX; anything cannot contain a newline.

   Typefaces
       grodvi  supports  the  standard  four  styles: R (roman), I (italic), B
       (bold), and BI (bold‐italic).  Fonts are grouped into families T and  H
       having members in each style.  “CM” abbreviates “Computer Modern”.

              TR     CM Roman (cmr10)
              TI     CM Text Italic (cmti10)
              TB     CM Bold Extended Roman (cmbx10)
              TBI    CM Bold Extended Text Italic (cmbxti10)
              HR     CM Sans Serif (cmss10)
              HI     CM Slanted Sans Serif (cmssi10)
              HB     CM Sans Serif Bold Extended (cmssbx10)
              HBI    CM Slanted Sans Serif Bold Extended (cmssbxo10)

       The following fonts are not members of a family.

              CW     CM Typewriter Text (cmtt10)
              CWI    CM Italic Typewriter Text (cmitt10)

       Special  fonts  include  MI  (cmmi10), S (cmsy10), EX (cmex10), SC (cm‐
       tex10, only for CW), and, perhaps surprisingly, TR, TI, and CW, because
       TeX places some glyphs in text fonts that  troff  generally  does  not.
       For italic fonts, CWI is used instead of CW.

       Finally,  the  symbol  fonts  of  the American Mathematical Society are
       available as special fonts SA (msam10) and SB (msbm10).  They  are  are
       not mounted by default.

       The  troff  option  -mec loads the ec.tmac macro file, employing the EC
       and TC fonts instead of CM.  These are designed similarly to  the  Com‐
       puter  Modern  fonts;  further,  they  provide Euro \[Eu] and per mille
       \[%0] glyphs.  ec.tmac must  be  loaded  before  any  language‐specific
       macro  files  because  it does not set up the codes necessary for auto‐
       matic hyphenation.

   Font description files
       Use tfmtodit(1) to create groff font description files  from  TFM  (TeX
       font metrics) files.  The font description file should contain the fol‐
       lowing additional directives, which tfmtodit generates automatically.

       internalname name
              The name of the TFM file (without the .tfm extension) is name.

       checksum n
              The checksum in the TFM file is n.

       designsize n
              The design size in the TFM file is n.

   Drawing commands
       grodvi supports an additional drawing command.

       \D'R dh dv'
              Draw a rule (solid black rectangle) with one corner at the draw‐
              ing  position, and the diagonally opposite corner at the drawing
              position +(dh,dv), which becomes the new drawing position after‐
              ward.  This command produces a rule in the DVI file and  so  can
              be  printed  even  with a driver that does not support tpic spe‐
              cials, unlike the other \D commands.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -d     Do  not  use tpic specials to implement drawing commands.  Hori‐
              zontal and vertical lines are implemented by rules.  Other draw‐
              ing commands are ignored.

       -F dir Prepend directory dir/devname to the search path  for  font  and
              device  description  files; name is the name of the device, usu‐
              ally dvi.

       -l     Use landscape orientation rather than portrait.

       -p paper‐format
              Set  physical  dimensions  of  output  medium,  overriding   the
              papersize,  paperlength,  and  paperwidth directives in the DESC
              file.   paper‐format  can  be  any  argument  accepted  by   the
              papersize directive; see groff_font(5).

       -w n   Draw  rules  (lines) with a thickness of n thousandths of an em.
              The default thickness is 40 (0.04 em).

Environment
       GROFF_FONT_PATH
              lists directories in which to search for devdvi, grodvi’s direc‐
              tory of device and font description  files.   See  troff(1)  and
              groff_font(5).

Files
       /usr/share/groff/1.23.0/font/devdvi/DESC
              describes the dvi output device.

       /usr/share/groff/1.23.0/font/devdvi/F
              describes the font known as F on device dvi.

       /usr/share/groff/1.23.0/tmac/dvi.tmac
              defines  font  mappings,  special characters, and colors for use
              with the dvi output  device.   It  is  automatically  loaded  by
              troffrc when the dvi output device is selected.

       /usr/share/groff/1.23.0/tmac/ec.tmac
              configures the dvi output device to use the EC and TC font fami‐
              lies instead of CM (Computer Modern).

Bugs
       DVI  files  produced by grodvi use a different resolution (57,816 units
       per inch) from those produced  by  TeX.   Incorrectly  written  drivers
       which  assume the resolution used by TeX, rather than using the resolu‐
       tion specified in the DVI file, will not work with grodvi.

       When using the -d option with boxed  tables,  vertical  and  horizontal
       lines  can  sometimes  protrude by one pixel.  This is a consequence of
       the way TeX requires that the heights and widths of rules be rounded.

See also
       “What are the EC fonts?”   ⟨https://texfaq.org/FAQ-ECfonts⟩;  TeX  FAQ:
       Frequently Asked Question List for TeX

       tfmtodit(1),    groff(1),    troff(1),   groff_out(5),   groff_font(5),
       groff_char(7), groff_tmac(5)

groff 1.23.0                      2 July 2023                        grodvi(1)
───────────────────────────────────────────────────────────────────────────────
groff(1)                    General Commands Manual                   groff(1)

Name
       groff - front end to the GNU roff document formatting system

Synopsis
       groff [-abcCeEgGijklNpRsStUVXzZ] [-d ctext] [-d string=text]
             [-D fallback‐encoding] [-f font‐family] [-F font‐directory]
             [-I inclusion‐directory] [-K input‐encoding] [-L spooler‐
             argument] [-m macro‐package] [-M macro‐directory] [-n page‐
             number] [-o page‐list] [-P postprocessor‐argument] [-r cnumeric‐
             expression] [-r register=numeric‐expression] [-T output‐device]
             [-w warning‐category] [-W warning‐category] [file ...]

       groff -h
       groff --help

       groff -v [option ...] [file ...]
       groff --version [option ...] [file ...]

Description
       groff is the primary front end to the GNU roff document formatting sys‐
       tem.  GNU roff is a typesetting system  that  reads  plain  text  input
       files that include formatting commands to produce output in PostScript,
       PDF,  HTML,  DVI, or other formats, or for display to a terminal.  For‐
       matting commands can be low‐level typesetting primitives, macros from a
       supplied package, or user‐defined macros.  All three approaches can  be
       combined.   If no file operands are specified, or if file is “-”, groff
       reads the standard input stream.

       A reimplementation and extension of  the  typesetter  from  AT&T  Unix,
       groff  is  present  on most POSIX systems owing to its long association
       with Unix manuals (including man pages).  It and  its  predecessor  are
       notable for their production of several best‐selling software engineer‐
       ing texts.  groff is capable of producing typographically sophisticated
       documents while consuming minimal system resources.

       The  groff  command  orchestrates  the  execution of preprocessors, the
       transformation of input documents into a  device‐independent  page  de‐
       scription language, and the production of output from that language.

Options
       -h and --help display a usage message and exit.

       Because  groff is intended to subsume most users’ direct invocations of
       the troff(1) formatter, the two programs share a set of options.   How‐
       ever,  groff  has  some  options  that troff does not share, and others
       which groff interprets differently.  At the same time,  not  all  valid
       troff options can be given to groff.

   groff‐specific options
       The  following  options  either do not exist in GNU troff or are inter‐
       preted differently by groff.

       -D enc Set fallback input encoding used by preconv(1) to  enc;  implies
              -k.

       -e     Run eqn(1) preprocessor.

       -g     Run grn(1) preprocessor.

       -G     Run grap(1) preprocessor; implies -p.

       -I dir Works as troff’s option (see below), but also implies -g and -s.
              It  is  passed  to  soelim(1)  and the output driver, and grn is
              passed an -M option with dir as its argument.

       -j     Run chem(1) preprocessor; implies -p.

       -k     Run preconv(1) preprocessor.  Refer to its man page for its  be‐
              havior if neither of groff’s -K or -D options is also specified.

       -K enc Set input encoding used by preconv(1) to enc; implies -k.

       -l     Send  the output to a spooler program for printing.  The “print”
              directive in the device description file specifies  the  default
              command  to be used; see groff_font(5).  If no such directive is
              present for the output device, output is piped to  lpr(1).   See
              options -L and -X.

       -L arg Pass arg to the print spooler program.  If multiple args are re‐
              quired,  pass  each  with  a separate -L option.  groff does not
              prefix an option dash to arg before passing it  to  the  spooler
              program.

       -M     Works  as  troff’s  option  (see  below),  but is also passed to
              eqn(1), grap(1), and grn(1).

       -N     Prohibit newlines between eqn delimiters: pass -N to eqn(1).

       -p     Run pic(1) preprocessor.

       -P arg Pass arg to the postprocessor.  If multiple args  are  required,
              pass  each  with a separate -P option.  groff does not prefix an
              option dash to arg before passing it to the postprocessor.

       -R     Run refer(1) preprocessor.  No mechanism is provided for passing
              arguments to refer because most refer  options  have  equivalent
              language elements that can be specified within the document.

       -s     Run soelim(1) preprocessor.

       -S     Operate in “safer” mode; see -U below for its opposite.  For se‐
              curity reasons, safer mode is enabled by default.

       -t     Run tbl(1) preprocessor.

       -T dev Direct  troff  to  format  the  input for the output device dev.
              groff then calls an output driver to convert troff’s output to a
              form appropriate for dev; see subsection “Output devices” below.

       -U     Operate in unsafe mode: pass the -U option to pic and troff.

       -v
       --version
              Write version information for groff and all programs run  by  it
              to  the  standard output stream; that is, the given command line
              is processed in the usual way, passing -v to the  formatter  and
              any pre‐ or postprocessors invoked.

       -V     Output  the pipeline that groff would run to the standard output
              stream, but do not execute it.  If given more than  once,  groff
              both writes and runs the pipeline.

       -X     Use gxditview(1) instead of the usual postprocessor to (pre)view
              a  document  on an X11 display.  Combining this option with -Tps
              uses the font metrics of  the  PostScript  device,  whereas  the
              -TX75 and -TX100 options use the metrics of X11 fonts.

       -Z     Disable  postprocessing.   troff output will appear on the stan‐
              dard output stream (unless suppressed with -z); see groff_out(5)
              for a description of this format.

   Transparent options
       The following  options  are  passed  as‐is  to  the  formatter  program
       troff(1) and described in more detail in its man page.

       -a     Generate a plain text approximation of the typeset output.

       -b     Write  a backtrace to the standard error stream on each error or
              warning.

       -c     Start with color output disabled.

       -C     Enable AT&T troff compatibility mode; implies -c.

       -d cs
       -d name=string
              Define string.

       -E     Inhibit troff error messages; implies -Ww.

       -f fam Set default font family.

       -F dir Search in directory dir for the selected output device’s  direc‐
              tory of device and font description files.

       -i     Process standard input after the specified input files.

       -I dir Search dir for input files.

       -m name
              Process name.tmac before input files.

       -M dir Search directory dir for macro files.

       -n num Number the first page num.

       -o list
              Output only pages in list.

       -r cnumeric‐expression
       -r register=numeric‐expression
              Define register.

       -w name
       -W name
              Enable  (-w)  or  inhibit  (-W) emission of warnings in category
              name.

       -z     Suppress formatted device‐independent output of troff.

Usage
       The architecture of the GNU roff system follows that of  other  device‐
       independent roff implementations, comprising preprocessors, macro pack‐
       ages,  output  drivers (or “postprocessors”), a suite of utilities, and
       the formatter troff at its heart.  See roff(7) for a survey  of  how  a
       roff system works.

       The  front end programs available in the GNU roff system make it easier
       to use  than  traditional  roffs  that  required  the  construction  of
       pipelines  or  use  of  temporary files to carry a source document from
       maintainable form to device‐ready output.  The discussion below  summa‐
       rizes  the  constituent  parts  of the GNU roff system.  It complements
       roff(7) with groff‐specific information.

   Getting started
       Those who prefer to learn by experimenting or  are  desirous  of  rapid
       feedback from the system may wish to start with a “Hello, world!” docu‐
       ment.

       $ echo "Hello, world!" | groff -Tascii | sed '/^$/d'
       Hello, world!

       We  used  a sed command only to eliminate the 65 blank lines that would
       otherwise flood the terminal screen.  (roff systems were  developed  in
       the days of paper‐based terminals with 66 lines to a page.)

       Today’s users may prefer output to a UTF‐8‐capable terminal.

       $ echo "Hello, world!" | groff -Tutf8 | sed '/^$/d'

       Producing  PDF,  HTML,  or TeX’s DVI is also straightforward.  The hard
       part may be selecting a viewer program for the output.

       $ echo "Hello, world!" | groff -Tpdf > hello.pdf
       $ evince hello.pdf
       $ echo "Hello, world!" | groff -Thtml > hello.html
       $ firefox hello.html
       $ echo "Hello, world!" | groff -Tdvi > hello.dvi
       $ xdvi hello.html

   Using groff as a REPL
       Those with a programmer’s bent may be pleased to know that they can use
       groff in a read‐evaluate‐print loop (REPL).  Doing so can be  handy  to
       verify  one’s understanding of the formatter’s behavior and/or the syn‐
       tax it accepts.  Turning on all warnings with -ww can aid this goal.

       $ groff -ww -Tutf8
       \# This is a comment. Let's define a register.
       .nr a 1
       \# Do integer arithmetic with operators evaluated left‐to‐right.
       .nr b \n[a]+5/2
       \# Let's get the result on the standard error stream.
       .tm \n[b]
       3
       \# Now we'll define a string.
       .ds name Leslie\" This is another form of comment.
       .nr b (\n[a] + (7/2))
       \# Center the next two text input lines.
       .ce 2
       Hi, \*[name].
       Your secret number is \n[b].
       \# We will see that the division rounded toward zero.
       It is
       \# Here's an if‐else control structure.
       .ie (\n[b] % 2) odd.
       .el even.
       \# This trick sets the page length to the current vertical
       \# position, so that blank lines don't spew when we're done.
       .pl \n[nl]u
       <Control‐D>
                                  Hi, Leslie.
                           Your secret number is 4.
       It is even.

   Paper format
       In GNU roff, the page dimensions for the formatter troff and for output
       devices are handled separately.  In the formatter, requests are used to
       set the page length (.pl), page offset (or left margin, .po), and  line
       length  (.ll).  The right margin is not explicitly configured; the com‐
       bination of page offset and line length provides the information neces‐
       sary to derive it.  The papersize macro package,  automatically  loaded
       by troff, provides an interface for configuring page dimensions by con‐
       venient  names,  like “letter” or “A4”; see groff_tmac(5).  The format‐
       ter’s default in this installation is “letter”.

       It is up to each macro package to respect the page  dimensions  config‐
       ured in this way.  Some offer alternative mechanisms.

       For each output device, the size of the output medium can be set in its
       DESC file.  Most output drivers also recognize a command‐line option -p
       to  override  the  default dimensions and an option -l to use landscape
       orientation.  See groff_font(5) for a description of the papersize  di‐
       rective,  which  takes  an argument of the same form as -p.  The output
       driver’s man page, such as grops(1), may also be helpful.   groff  uses
       the command‐line option -P to pass options to output devices; for exam‐
       ple,  use  the following for PostScript output on A4 paper in landscape
       orientation.

              groff -Tps -dpaper=a4l -P-pa4 -P-l -ms foo.ms > foo.ps

   Front end
       The groff program is a wrapper around the troff(1) program.  It  allows
       one to specify preprocessors via command‐line options and automatically
       runs the appropriate postprocessor for the selected output device.  Do‐
       ing so, the manual construction of pipelines or management of temporary
       files  required of users of traditional roff(7) systems can be avoided.
       Use the grog(1) program to infer an appropriate groff command  line  to
       format a document.

   Language
       Input  to a roff system is in plain text interleaved with control lines
       and escape sequences.  The combination constitutes a document in one of
       a family of languages we also call roff; see  roff(7)  for  background.
       An  overview  of GNU roff language syntax and features, including lists
       of all supported escape sequences, requests, and predefined  registers,
       can  be  found in groff(7).  GNU roff extensions to the AT&T troff lan‐
       guage, a common subset of roff dialects extant today, are  detailed  in
       groff_diff(7).

   Preprocessors
       A preprocessor interprets a domain‐specific language that produces roff
       language output.  Frequently, such input is confined to sections or re‐
       gions of a roff input file (bracketed with macro calls specific to each
       preprocessor), which it replaces.  Preprocessors therefore often inter‐
       pret  a  subset of roff syntax along with their own language.  GNU roff
       provides reimplementations of most preprocessors familiar to  users  of
       AT&T  troff;  these routinely have extended features and/or require GNU
       troff to format their output.

              tbl         lays out tables;
              eqn         typesets mathematics;
              pic         draws diagrams;
              refer       processes bibliographic references;
              soelim      preprocesses “sourced” input files;
              grn         renders gremlin(1) diagrams;
              chem        draws chemical structural formulæ using pic;
              gperl       populates groff registers and strings using perl(1);
              glilypond   embeds LilyPond sheet music; and
              gpinyin     eases Mandarin Chinese input using Hanyu Pinyin.

       A preprocessor unique to GNU roff is preconv(1), which converts various
       input encodings to something GNU troff can understand.  When  used,  it
       is run before any other preprocessors.

       Most preprocessors enclose content between a pair of characteristic to‐
       kens.   Such  a  token must occur at the beginning of an input line and
       use the dot control character.  Spaces and tabs  must  not  follow  the
       control character or precede the end of the input line.  Deviating from
       these  rules defeats a token’s recognition by the preprocessor.  Tokens
       are generally preserved in preprocessor output and interpreted as macro
       calls subsequently by troff.  The ideal preprocessor is not yet  avail‐
       able in groff.

                ┌──────────────┬─────────────────┬────────────────┐
                │ preprocessor │ starting token  │  ending token  │
                ├──────────────┼─────────────────┼────────────────┤
                │     chem     │     .cstart     │     .cend      │
                │     eqn      │       .EQ       │      .EN       │
                │     grap     │       .G1       │      .G2       │
                │     grn      │       .GS       │      .GE       │
                │    ideal     │       .IS       │      .IE       │
                │              │                 │      .IF       │
                │     pic      │       .PS       │      .PE       │
                │              │                 │      .PF       │
                │              │                 │      .PY       │
                │    refer     │       .R1       │      .R2       │
                │     tbl      │       .TS       │      .TE       │
                ├──────────────┼─────────────────┼────────────────┤
                │  glilypond   │ .lilypond start │ .lilypond stop │
                │    gperl     │   .Perl start   │   .Perl stop   │
                │   gpinyin    │  .pinyin start  │  .pinyin stop  │
                └──────────────┴─────────────────┴────────────────┘

   Macro packages
       Macro  files  are  roff input files designed to produce no output them‐
       selves but instead ease the preparation of other roff documents.   When
       a  macro  file is installed at a standard location and suitable for use
       by a general audience, it is termed a macro package.

       Macro packages can be loaded prior to any roff input documents with the
       -m option.  The GNU roff system implements most well‐known macro  pack‐
       ages  for  AT&T troff in a compatible way and extends them.  These have
       one‐ or two‐letter names arising from intense practices of naming econ‐
       omy in early Unix culture, a laconic approach that led to many  of  the
       packages being identified in general usage with the nroff and troff op‐
       tion  letter  used to invoke them, sometimes to punning effect, as with
       “man” (short for “manual”), and even with the option dash,  as  in  the
       case of the s package, much better known as ms or even -ms.

       Macro  packages  serve  a variety of purposes.  Some are “full‐service”
       packages, adopting responsibility for page layout among other fundamen‐
       tal tasks, and defining their own lexicon of macros for document compo‐
       sition; each such package stands alone and a given document can use  at
       most one.

       an     is  used  to compose man pages in the format originating in Ver‐
              sion 7 Unix (1979); see groff_man(7).  It can  be  specified  on
              the command line as -man.

       doc    is  used  to  compose  man  pages  in  the format originating in
              4.3BSD‐Reno (1990); see groff_mdoc(7).  It can be  specified  on
              the command line as -mdoc.

       e      is the Berkeley general‐purpose macro suite, developed as an al‐
              ternative  to AT&T’s s; see groff_me(7).  It can be specified on
              the command line as -me.

       m      implements the format used by the second‐generation  AT&T  macro
              suite  for general documents, a successor to s; see groff_mm(7).
              It can be specified on the command line as -mm.

       om     (invariably called “mom”) is a modern package written  by  Peter
              Schaffter  specifically for GNU roff.  Consult the mom HTML man‐
              ual  ⟨file:///usr/share/doc/groff-1.23.0/html/mom/toc.html⟩  for
              extensive  documentation.  She—for mom takes the female pronoun—
              can be specified on the command line as -mom.

       s      is  the  original  AT&T  general‐purpose  document  format;  see
              groff_ms(7).  It can be specified on the command line as -ms.

       Others are supplemental.  For instance, andoc is a wrapper package spe‐
       cific  to  GNU roff that recognizes whether a document uses man or mdoc
       format and loads the corresponding macro package.  It can be  specified
       on  the  command  line  as -mandoc.  A man(1) librarian program may use
       this macro file to delegate loading of the correct macro package; it is
       thus unnecessary for man itself to scan the contents of a  document  to
       decide the issue.

       Many  macro files augment the function of the full‐service packages, or
       of roff documents that do not employ  such  a  package—the  latter  are
       sometimes  characterized  as  “raw”.   These auxiliary packages are de‐
       scribed, along with details of macro  file  naming  and  placement,  in
       groff_tmac(5).

   Formatters
       The  formatter,  the  program  that  interprets roff language input, is
       troff(1).  It provides the features of the AT&T troff  and  nroff  pro‐
       grams  as well as many extensions.  The command‐line option -C switches
       troff into compatibility mode, which tries to  emulate  AT&T  troff  as
       closely  as  is practical to enable the formatting of documents written
       for the older system.

       A shell script, nroff(1), emulates the behavior of AT&T nroff.  It  at‐
       tempts  to  correctly  encode the output based on the locale, relieving
       the user of the need to specify an output device with the -T option and
       is therefore convenient for use with terminal output devices, described
       in the next subsection.

       GNU troff generates output in a device‐independent, but not  device‐ag‐
       nostic, page description language detailed in groff_out(5).

   Output devices
       troff  output  is  formatted  for a particular output device, typically
       specified by the -T option to the formatter or a front end.  If neither
       this option nor the GROFF_TYPESETTER environment variable is used,  the
       default  output  device is ps.  An output device may be any of the fol‐
       lowing.

       ascii    for terminals using the ISO 646 1991:IRV character set and en‐
                coding, also known as US‐ASCII.

       cp1047   for terminals using the IBM code page 1047 character  set  and
                encoding.

       dvi      for TeX DVI format.

       html
       xhtml    for HTML and XHTML output, respectively.

       latin1   for terminals using the ISO Latin‐1 (ISO 8859‐1) character set
                and encoding.

       lbp      for  Canon CaPSL printers (LBP‐4 and LBP‐8 series laser print‐
                ers).

       lj4      for HP LaserJet4‐compatible (or other PCL5‐compatible)  print‐
                ers.

       pdf      for PDF output.

       ps       for PostScript output.

       utf8     for terminals using the ISO 10646 (“Unicode”) character set in
                UTF‐8 encoding.

       X75      for  previewing  with  gxditview using 75 dpi resolution and a
                10‐point base type size.

       X75-12   for previewing with gxditview using 75 dpi  resolution  and  a
                12‐point base type size.

       X100     for  previewing  with gxditview using 100 dpi resolution and a
                10‐point base type size.

       X100-12  for previewing with gxditview using 100 dpi resolution  and  a
                12‐point base type size.

   Postprocessors
       Any program that interprets the output of GNU troff is a postprocessor.
       The  postprocessors provided by GNU roff are output drivers, which pre‐
       pare a document for viewing or printing.  Postprocessors for other pur‐
       poses, such as page resequencing or statistical measurement of a  docu‐
       ment, are conceivable.

       An output driver supports one or more output devices, each with its own
       device  description  file.   A device determines its postprocessor with
       the  postpro  directive   in   its   device   description   file;   see
       groff_font(5).    The  -X  option  overrides  this  selection,  causing
       gxditview to serve as the output driver.

       grodvi(1)
              provides dvi.

       grohtml(1)
              provides html and xhtml.

       grolbp(1)
              provides lbp.

       grolj4(1)
              provides lj4.

       gropdf(1)
              provides pdf.

       grops(1)
              provides ps.

       grotty(1)
              provides ascii, cp1047, latin1, and utf8.

       gxditview(1)
              provides X75, X75-12, X100, and X100-12,  and  additionally  can
              preview ps.

   Utilities
       GNU roff includes a suite of utilities.

       gdiffmk(1)
              marks differences between a pair of roff input files.

       grog(1)
              infers the groff command a document requires.

       Several utilities prepare descriptions of fonts, enabling the formatter
       to use them when producing output for a given device.

       addftinfo(1)
              adds  information to AT&T troff font description files to enable
              their use with GNU troff.

       afmtodit(1)
              creates font description files for PostScript Type 1 fonts.

       pfbtops(1)
              translates a PostScript Type 1 font in PFB (Printer Font Binary)
              format to PFA (Printer Font ASCII), which  can  then  be  inter‐
              preted by afmtodit.

       hpftodit(1)
              creates  font  description files for the HP LaserJet 4 family of
              printers.

       tfmtodit(1)
              creates font description files for the TeX DVI device.

       xtotroff(1)
              creates font description files for X Window System core fonts.

       A trio of tools transform material constructed using roff  preprocessor
       languages into graphical image files.

       eqn2graph(1)
              converts an eqn equation into a cropped image.

       grap2graph(1)
              converts a grap diagram into a cropped image.

       pic2graph(1)
              converts a pic diagram into a cropped image.

       Another set of programs works with the bibliographic data files used by
       the refer(1) preprocessor.

       indxbib(1)
              makes  inverted  indices  for  bibliographic databases, speeding
              lookup operations on them.

       lkbib(1)
              searches the databases.

       lookbib(1)
              interactively searches the databases.

Exit status
       groff exits with a failure status if there was a  problem  parsing  its
       arguments and a successful status if either of the options -h or --help
       was  specified.  Otherwise, groff runs a pipeline to process its input;
       if all commands within the pipeline exit successfully, groff does like‐
       wise.  If not, groff’s exit status encodes a summary  of  problems  en‐
       countered,  setting  bit  0  if a command exited with a failure status,
       bit 1 if a command was terminated with a signal, and bit 2 if a command
       could not be executed.  (Thus, if all three  misfortunes  befell  one’s
       pipeline,  groff  would  exit with status 2^0 + 2^1 + 2^2 = 1+2+4 = 7.)
       To troubleshoot pipeline problems, you may wish  to  re‐run  the  groff
       command  with  the  -V option and break the reported pipeline down into
       separate stages, inspecting the exit status of and diagnostic  messages
       emitted by each command.

Environment
       Normally,  the path separator in environment variables ending with PATH
       is the colon; this may vary depending on the operating system.  For ex‐
       ample, Windows uses a semicolon instead.

       GROFF_BIN_PATH
              This search path, followed by PATH, is used to  locate  commands
              executed by groff.  If it is not set, the installation directory
              of the GNU roff executables, /usr/bin, is searched before PATH.

       GROFF_COMMAND_PREFIX
              GNU  roff can be configured at compile time to apply a prefix to
              the names of the programs it provides that had a counterpart  in
              AT&T  troff,  so  that  name collisions are avoided at run time.
              The default prefix is empty.

              When used, this prefix is conventionally the  letter  “g”.   For
              example, GNU troff would be installed as gtroff.  Besides troff,
              the  prefix  applies  to  the formatter nroff; the preprocessors
              eqn, grn, pic, refer, tbl, and soelim; and the utilities indxbib
              and lookbib.

       GROFF_ENCODING
              The value of this variable is  passed  to  the  preconv(1)  pre‐
              processor’s  -e option to select the character encoding of input
              files.  This variable’s existence implies the groff  option  -k.
              If  set  but  empty,  groff  calls preconv without an -e option.
              groff’s -K option overrides GROFF_ENCODING.

       GROFF_FONT_PATH
              Seek the selected output device’s directory of device  and  font
              description files in this list of directories.  See troff(1) and
              groff_font(5).

       GROFF_TMAC_PATH
              Seek  macro files in this list of directories.  See troff(1) and
              groff_tmac(5).

       GROFF_TMPDIR
              Create temporary files in this directory.  If not set,  but  the
              environment  variable TMPDIR is set, temporary files are created
              there instead.  On Windows systems, if neither of the  foregoing
              are  set, the environment variables TMP and TEMP (in that order)
              are checked also.  Otherwise, temporary  files  are  created  in
              /tmp.   The refer(1), grohtml(1), and grops(1) commands use tem‐
              porary files.

       GROFF_TYPESETTER
              Set the default output device.  If empty or not set, ps is used.
              The -T option overrides GROFF_TYPESETTER.

       SOURCE_DATE_EPOCH
              A time stamp (expressed as seconds since the Unix epoch) to  use
              as  the output creation time stamp in place of the current time.
              The time is converted to human‐readable form using  localtime(3)
              when  the  formatter starts up and stored in registers usable by
              documents and macro packages.

       TZ     The time zone to use when converting the current time (or  value
              of SOURCE_DATE_EPOCH) to human‐readable form; see tzset(3).

Examples
       roff  systems  are  best known for formatting man pages.  Once a man(1)
       librarian program has located a man page, it may execute a  groff  com‐
       mand much like the following.
              groff -t -man -Tutf8 /usr/share/man/man1/groff.1
       The  librarian  will  also pipe the output through a pager, which might
       not interpret the SGR terminal escape sequences groff emits  for  bold‐
       face, underlining, or italics; see section “Limitations” below.

       To  process  a  roff input file using the preprocessors tbl and pic and
       the me macro package in the way to which AT&T troff users  were  accus‐
       tomed, one would type (or script) a pipeline.

              pic foo.me | tbl | troff -me -Tutf8 | grotty

       Using groff, this pipe can be shortened to an equivalent command.

              groff -p -t -me -T utf8 foo.me

       An even easier way to do this is to use grog(1) to guess the preproces‐
       sor  and macro options and execute the result by using the command sub‐
       stitution feature of the shell.

              $(grog -Tutf8 foo.me)

       Each command‐line option to a postprocessor must be specified with  any
       required leading dashes “-” because groff passes the arguments as‐is to
       the  postprocessor; this permits arbitrary arguments to be transmitted.
       For example, to pass a title to the gxditview postprocessor, the  shell
       commands
              groff -X -P -title -P 'trial run' mydoc.t
       and
              groff -X -Z mydoc.t | gxditview -title 'trial run' -
       are equivalent.

Limitations
       When  paging  output  for  the ascii, cp1047, latin1, and utf8 devices,
       programs like more(1) and less(1) may require command‐line  options  to
       correctly handle some terminal escape sequences; see grotty(1).

       On  EBCDIC  hosts  such  as  OS/390  Unix, the output devices ascii and
       latin1 aren’t available.  Conversely, the output device cp1047  is  not
       available  on systems based on the ISO 646 or ISO 8859 character encod‐
       ing standards.

Installation directories
       GNU roff installs files in varying locations depending on its  compile‐
       time  configuration.  On this installation, the following locations are
       used.

       /etc/X11/app-defaults
              Application defaults directory for gxditview(1).

       /usr/bin
              Directory containing groff’s executable commands.

       /usr/share/groff/1.23.0/eign
              List of common words for indxbib(1).

       /usr/share/groff/1.23.0
              Directory for data files.

       /usr/dict/papers/Ind
              Default index for lkbib(1) and refer(1).

       /usr/share/doc/groff-1.23.0
              Documentation directory.

       /usr/share/doc/groff-1.23.0/examples
              Example directory.

       /usr/share/groff/1.23.0/font
              Font directory.

       /usr/share/doc/groff-1.23.0/html
              HTML documentation directory.

       /usr/lib/font
              Legacy font directory.

       /usr/share/groff/site-font
              Local font directory.

       /usr/share/groff/site-tmac
              Local macro package (tmac file) directory.

       /usr/share/groff/1.23.0/tmac
              Macro package (tmac file) directory.

       /usr/share/groff/1.23.0/oldfont
              Font directory for compatibility with old versions of groff; see
              grops(1).

       /usr/share/doc/groff-1.23.0/pdf
              PDF documentation directory.

   groff macro directory
       Most macro files supplied with GNU roff are stored in /usr/share/groff/
       1.23.0/tmac for the installation corresponding to this document.  As  a
       rule,  multiple directories are searched for macro files; see troff(1).
       For a catalog of macro files GNU roff provides, see groff_tmac(5).

   groff device and font description directory
       Device and font description files supplied with GNU roff are stored  in
       /usr/share/groff/1.23.0/font for the installation corresponding to this
       document.   As a rule, multiple directories are searched for device and
       font description files; see troff(1).  For the formats of these  files,
       see groff_font(5).

Availability
       Obtain  links  to  groff  releases for download, its source repository,
       discussion mailing lists, a support ticket tracker, and further  infor‐
       mation  from  the  groff  page  of the GNU website ⟨http://www.gnu.org/
       software/groff⟩.

       A free implementation of the grap preprocessor, written  by  Ted  Faber
       ⟨faber@lunabase.org⟩,  can  be  found  at  the grap website ⟨http://www
       .lunabase.org/~faber/Vault/software/grap/⟩.  groff supports  only  this
       grap.

Authors
       groff (both the front‐end command and the overall system) was primarily
       written by James Clark ⟨jjc@jclark.com⟩.  Contributors to this document
       include  Clark,  Trent  A.  Fisher,  Werner Lemberg ⟨wl@gnu.org⟩, Bernd
       Warken  ⟨groff-bernd.warken-72@web.de⟩,   and   G.   Branden   Robinson
       ⟨g.branden.robinson@gmail.com⟩.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       Introduction, history, and further reading:
              roff(7)

       Viewer for groff (and AT&T device‐independent troff) documents:
              gxditview(1)

       Preprocessors:
              chem(1),  eqn(1),  neqn(1),  glilypond(1),  grn(1),  preconv(1),
              gperl(1), pic(1), gpinyin(1), refer(1), soelim(1), tbl(1)

       Macro packages and package‐specific utilities:
              groff_hdtbl(7), groff_man(7), groff_man_style(7), groff_mdoc(7),
              groff_me(7),     groff_mm(7),     groff_mmse(7),      mmroff(1),
              groff_mom(7),    pdfmom(1),    groff_ms(7),    groff_rfc1345(7),
              groff_trace(7), groff_www(7)

       Bibliographic database management tools:
              indxbib(1), lkbib(1), lookbib(1)

       Language, conventions, and GNU extensions:
              groff(7),    groff_char(7),    groff_diff(7),     groff_font(5),
              groff_tmac(5)

       Intermediate output language:
              groff_out(5)

       Formatter program:
              troff(1)

       Formatter wrappers:
              nroff(1), pdfroff(1)

       Postprocessors for output devices:
              grodvi(1),    grohtml(1),   grolbp(1),   grolj4(1),   gropdf(1),
              grops(1), grotty(1)

       Font support utilities:
              addftinfo(1), afmtodit(1), hpftodit(1), pfbtops(1), tfmtodit(1),
              xtotroff(1)

       Graphics conversion utilities:
              eqn2graph(1), grap2graph(1), pic2graph(1)

       Difference‐marking utility:
              gdiffmk(1)

       “groff guess” utility:
              grog(1)

groff 1.23.0                      2 July 2023                         groff(1)
───────────────────────────────────────────────────────────────────────────────
grog(1)                     General Commands Manual                    grog(1)

Name
       grog - “groff guess”—infer the groff command a document requires

Synopsis
       grog [--run] [--ligatures] [groff‐option ...] [--] [file ...]

       grog -h
       grog --help

       grog -v
       grog --version

Description
       grog reads its input and guesses which groff(1) options are  needed  to
       render it.  If no operands are given, or if file is “-”, grog reads the
       standard  input  stream.   The  corresponding groff command is normally
       written to the standard output stream.  With the option --run, the  in‐
       ferred  command  is  written to the standard error stream and then exe‐
       cuted.

Options
       -h and --help display a usage message, whereas -v and --version display
       version information; all exit afterward.

       --ligatures
              includes the arguments -P-y -PU in the inferred  groff  command.
              These are supported only by the pdf output device.

       --run  writes  the  inferred  command  to the standard error stream and
              then executes it.

       All other specified short options (that is, arguments beginning with  a
       minus  sign  “-” followed by a letter) are interpreted as groff options
       or option clusters with or without an option  argument.   Such  options
       are included in the constructed groff command line.

Details
       grog reads each file operand, pattern‐matching strings that are statis‐
       tically  likely to be characteristic of roff(7) documents.  It tries to
       guess which of the following groff options are  required  to  correctly
       render the input: -e, -g, -G, -j, -p, -R, -t (preprocessors); and -man,
       -mdoc,  -mdoc-old,  -me,  -mm, -mom, and -ms (macro packages).  The in‐
       ferred groff command including these options and any file parameters is
       written to the standard output stream.

       It is possible to specify arbitrary groff options on the command  line.
       These  are included in the inferred command without change.  Choices of
       groff options include -C to enable AT&T troff compatibility mode and -T
       to select a non‐default output device.  If the input is not encoded  in
       US‐ASCII,  ISO  8859‐1, or IBM code page 1047, specification of a groff
       option to run the preconv(1) preprocessor is advised; see the  -D,  -k,
       and -K options of groff(1).  For UTF‐8 input, -k is a good choice.

       groff may issue diagnostic messages when an inappropriate -m option, or
       multiple  conflicting ones, are specified.  Consequently, it is best to
       specify no -m options to grog unless it cannot correctly infer  all  of
       the  -m  arguments  a  document  requires.  A roff document can also be
       written without recourse to any macro package.   In  such  cases,  grog
       will infer a groff command without an -m option.

   Limitations
       grog  presumes  that  the input does not change the escape, control, or
       no‐break control characters.  grog does not parse roff input line  con‐
       tinuation  or  control structures (brace escape sequences and the “if”,
       “ie”, and “el” requests) nor groff’s “while”.  Thus the input
              .if \
              t .NH 1
              .if n .SH
              Introduction
       will conceal the use of the ms macros NH and SH from grog.   Such  con‐
       structions are regarded by grog’s implementors as insufficiently common
       to  cause  many inference problems.  Preprocessors can be even stricter
       when matching macro calls that bracket the regions  of  an  input  file
       they replace.  pic, for example, requires PS, PE, and PF calls to imme‐
       diately  follow  the  default  control  character at the beginning of a
       line.

       Detection of the -s option (the soelim(1) preprocessor) is  tricky;  to
       correctly  infer  its  necessity would require grog to recursively open
       all files given as arguments to the .so request under the  same  condi‐
       tions that soelim itself does so; see its man page.  Recall that soelim
       is necessary only if sourced files need to be preprocessed.  Therefore,
       as a workaround, you may want to run the input through soelim manually,
       piping  it to grog, and compare the output to running grog on the input
       directly.  If the “soelim”ed input causes grog to infer additional pre‐
       processor options, then -s is likely necessary.

              $ printf ".TS\nl.\nI'm a table.\n.TE\n" > 3.roff
              $ printf ".so 3.roff\n" > 2.roff
              $ printf ".XP\n.so 2.roff\n" > 1.roff
              $ grog 1.roff
              groff -ms 1.roff
              $ soelim 1.roff | grog
              groff -t -ms -

       In the foregoing example, we see that this procedure  enabled  grog  to
       detect tbl(1) macros, so we would add -s as well as the detected -t op‐
       tion to a revised grog or groff command.

              $ grog -st 1.roff
              groff -st -ms 1.roff

Exit status
       grog  exits with error status 1 if a macro package appears to be in use
       by the input document, but grog was unable to infer which one, or 2  if
       there  were problems handling an option or operand.  It otherwise exits
       with status 0.  (If the --run option is specified, groff’s exit  status
       is  discarded.)  Inferring no preprocessors or macro packages is not an
       error condition; a valid roff document need not use either.  Even plain
       text is valid input, if one is mindful of the syntax of the control and
       escape characters.

Examples
       Running
              grog /usr/share/doc/groff-1.23.0/meintro.me
       at the command line results in
              groff -me /usr/share/doc/groff-1.23.0/meintro.me
       because grog recognizes that  the  file  meintro.me  is  written  using
       macros from the me package.  The command
              grog /usr/share/doc/groff-1.23.0/pic.ms
       outputs
              groff -e -p -t -ms /usr/share/doc/groff-1.23.0/pic.ms
       on  the other hand.  Besides discerning the ms macro package, grog rec‐
       ognizes that the file pic.ms additionally needs the combination  of  -t
       for tbl, -e for eqn, and -p for pic.

       Consider  a  file  doc/grnexampl.me, which uses the grn preprocessor to
       include a gremlin(1) picture file in an me document.  Let’s say we want
       to suppress color output, produce a DVI file, and  get  backtraces  for
       any errors that troff encounters.  The command
              grog -bc -Idoc -Tdvi doc/grnexmpl.me
       is processed by grog into
              groff -bc -Idoc -Tdvi -e -g -me doc/grnexmpl.me
       where we can see that grog has inferred the me macro package along with
       the  eqn  and  grn  preprocessors.  (The input file is located in /usr/
       share/doc/groff-1.23.0 if you’d like to try this example yourself.)

Authors
       grog was originally written in Bourne shell by James Clark.   The  cur‐
       rent  implementation  in  Perl was written by Bernd Warken ⟨groff-bernd
       .warken-72@web.de⟩  and  heavily  revised  by   G.   Branden   Robinson
       ⟨g.branden.robinson@gmail.com⟩.

See also
       groff(1)

groff 1.23.0                      2 July 2023                          grog(1)
───────────────────────────────────────────────────────────────────────────────
grohtml(1)                  General Commands Manual                 grohtml(1)

Name
       grohtml, post-grohtml, pre-grohtml - groff output driver for HTML

Synopsis
       pre-grohtml [-epV] [-a anti‐aliasing‐text‐bits] [-D image‐directory]
                   [-F font‐directory] [-g anti‐aliasing‐graphic‐bits] [-i
                   resolution] [-I image‐stem] [-o image‐vertical‐offset] [-x
                   html‐dialect] troff‐command troff‐argument ...

       pre-grohtml --help

       pre-grohtml -v
       pre-grohtml --version

       post-grohtml [-bCGhlnrVy] [-F font‐directory] [-j output‐stem] [-s
                    base‐point‐size] [-S heading‐level] [-x html‐dialect]
                    [file ...]

       post-grohtml --help

       post-grohtml -v
       post-grohtml --version

Description
       The  GNU  roff  system’s  HTML  support  consists  of  a  preprocessor,
       pre-grohtml, and an output driver, post-grohtml; together, they  trans‐
       late  roff(7)  documents to HTML.  Because a preprocessor is (uniquely)
       required for this output driver, users should invoke  grohtml  via  the
       groff(1)  command with the -Thtml or -Txhtml options.  (In this instal‐
       lation, ps is the default output device.)  Use  groff’s  -P  option  to
       pass  any options shown above to grohtml.  If no operands are given, or
       if file is “-”, grohtml reads the standard  input  stream.   Output  is
       written to the standard output stream.

       grohtml  invokes  groff  twice.   In  the  first pass, the preprocessor
       pre-grohtml renders pictures, equations, and tables as images in  Post‐
       Script format using the ps output device.  In the second pass, the out‐
       put driver post-grohtml translates the output of troff(1) to HTML.

       grohtml  writes  output encoded in UTF‐8 and has built‐in HTML entities
       for all non‐composite Unicode characters.  In spite of this, groff  may
       issue  warnings about unknown special characters if they can’t be found
       during the first pass.  Such warnings can be safely ignored unless  the
       special characters appear inside a table or equation.

   Typefaces
       grohtml  supports  the  standard  four styles: R (roman), I (italic), B
       (bold), and BI (bold‐italic).  Fonts are grouped into families T and  C
       having members in each style.

              TR     Times roman
              TI     Times italic
              TB     Times bold
              TBI    Times bold‐italic
              CR     Courier roman
              CI     Courier italic
              CB     Courier bold
              CBI    Courier bold‐italic

       A  special font, S, is also provided to accommodate roff documents that
       expect it to always be available.

   Font description files
       The font description files used with  grohtml  expose  the  same  glyph
       repertoire in their charset sections.  See groff_font(5).

   Dependencies
       pre-grohtml  generates an image whenever an eqn equation, tbl table, or
       pic picture is encountered in the input.   grohtml  therefore  may  run
       several  commands  as  part of its operation.  These include the Netpbm
       tools pnmcrop, pnmcut, and pnmtopng; Ghostscript (gs); and the  PSUtils
       tool psselect.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -a anti‐aliasing‐text‐bits
              Number of bits of antialiasing information to be  used  by  text
              when  generating  PNG  images.  The default is 4 but 0, 1, and 2
              are also valid.  Your system’s version of gs  must  support  the
              -dTextAlphaBits  option  in  order  to  exploit antialiasing.  A
              value of 0 stops grohtml from issuing antialiasing  commands  to
              gs.

       -b     Initialize the background color to white.

       -C     Suppress output of “CreationDate:” HTML comment.

       -D image‐directory
              Instruct  grohtml to place all image files into directory image‐
              directory.

       -e     Direct eqn to produce MathML.

              This option should not be manually specified; it is  synthesized
              by groff depending on whether it was given the -Thtml or -Txhtml
              option.

       -F font‐directory
              Prepend  directory font‐directory/devname to the search path for
              font and device description files; name is the name of  the  de‐
              vice, usually html.

       -g anti‐aliasing‐graphic‐bits
              Number  of bits of antialiasing information to be used by graph‐
              ics when generating PNG images.  The default is 4 but 0, 1,  and
              2  are also valid.  Your system’s version of gs must support the
              -dGraphicAlphaBits option in order to exploit  antialiasing.   A
              value  of  0 stops grohtml from issuing antialiasing commands to
              gs.

       -G     Suppress output of “Creator:” HTML comment.

       -h     Generate section headings by using HTML B elements and  increas‐
              ing the font size, rather than HTML H elements.

       -i resolution
              Set the image resolution in pixels per inch; the default is 100.

       -I image‐stem
              Determine  the  image  file name stem.  If omitted, grohtml uses
              grohtml-XXXXX (where XXXXX is the process ID).  A  dash  is  ap‐
              pended  to the stem to separate it from the following image num‐
              ber.

       -j output‐stem
              Instruct grohtml to split the HTML output into  multiple  files.
              Output is written to a new file at each section heading (but see
              option -S below) named output‐stem-n.html.

       -l     Turn off the production of automatic section links at the top of
              the document.

       -n     Generate  simple heading anchors whenever a section/number head‐
              ing is found.  Without the option the anchor value is  the  tex‐
              tual heading.  This can cause problems when a heading contains a
              “?”  on  older versions of some browsers.  This feature is auto‐
              matically enabled if a heading contains an image.

       -o image‐vertical‐offset
              Specify the vertical offset of images in points.

       -p     Display page rendering progress to the  standard  error  stream.
              grohtml displays a page number only when an image is required.

       -r     Turn off the automatic header and footer line (HTML rule).

       -s base‐type‐size
              Set  the document’s base type size in points.  When this size is
              used in the source, it corresponds to the HTML base  type  size.
              Every  increase of two points in the source will produce a “big”
              element, and conversely when a decrease of two points is seen, a
              “small” element is emitted.

       -S heading‐level
              When splitting HTML output (see option -j above), split at  each
              nested  heading level defined by heading‐level, or higher).  The
              default is 1.

       -V     Create an XHTML or HTML validator button at the bottom  of  each
              page of the document.

       -x html‐dialect
              Select  HTML  dialect.  Currently, html‐dialect should be either
              the digit 4 or the letter x,  which  indicates  whether  grohtml
              should generate HTML 4 or XHTML, respectively.

              This  option should not be manually specified; it is synthesized
              by groff depending on whether it was given the -Thtml or -Txhtml
              option.

       -y     Produce a right‐aligned groff signature at the end of the  docu‐
              ment (only if -V is also specified).

Environment
       GROFF_FONT_PATH
              lists  directories in which to search for devhtml, grohtml’s di‐
              rectory of device and font description files.  See troff(1)  and
              groff_font(5).

       SOURCE_DATE_EPOCH
              A  timestamp  (expressed as seconds since the Unix epoch) to use
              as the output creation timestamp in place of the  current  time.
              The  time is converted to human‐readable form using ctime(3) and
              recorded in an HTML comment.

       TZ     The time zone to use when converting the current time (or  value
              of SOURCE_DATE_EPOCH) to human‐readable form; see tzset(3).

Files
       /usr/share/groff/1.23.0/font/devhtml/DESC
              describes the html output device.

       /usr/share/groff/1.23.0/font/devhtml/F
              describes the font known as F on device html.

       /usr/share/groff/1.23.0/tmac/html.tmac
              defines  font  mappings,  special characters, and colors for use
              with the html output device.   It  is  automatically  loaded  by
              troffrc  when  either of the html or xhtml output devices is se‐
              lected.

       /usr/share/groff/1.23.0/tmac/html-end.tmac
              finalizes setup of the html output device.  It is  automatically
              loaded  by  troffrc-end  when either of the html or xhtml output
              devices is selected.

       grohtml uses temporary files.  See groff(1)  for  details  about  where
       such files are created.

Bugs
       grohtml is still beta code.

       grohtml  does  not  truly support hyphenation, but you can fool it into
       hyphenating long input lines, which can appear in HTML  output  with  a
       hyphenated word followed by a space but no line break.

See also
       groff(1), troff(1), groff_font(5)

groff 1.23.0                      2 July 2023                       grohtml(1)
───────────────────────────────────────────────────────────────────────────────
grolbp(1)                   General Commands Manual                  grolbp(1)

Name
       grolbp - groff output driver for Canon CaPSL printers

Synopsis
       grolbp [-l] [-c num‐copies] [-F font‐directory] [-o orientation]
              [-p paper‐format] [-w width] [file ...]
       grolbp [--copies=num‐copies] [--fontdir=font‐directory] [--landscape]
              [--linewidth=width] [--orientation=orientation]
              [--papersize=paper‐format] [file ...]

       grolbp -h
       grolbp --help

       grolbp -v
       grolbp --version

Description
       This  GNU  roff  output driver translates the output of troff(1) into a
       CaPSL and VDM format suitable for Canon LBP‐4 and LBP‐8 printers.  Nor‐
       mally, grolbp is invoked by groff(1)  when  the  latter  is  given  the
       “-T  lbp”  option.  (In this installation, ps is the default output de‐
       vice.)  Use groff’s -P option  to  pass  any  options  shown  above  to
       grolbp.   If  no  file  arguments  are given, or if file is “-”, grolbp
       reads the standard input stream.  Output is  written  to  the  standard
       output stream.

   Typefaces
       The  driver  supports the Dutch, Swiss, and Swiss‐Narrow scalable type‐
       faces, each in the regular, bold, italic, and bold‐italic styles.   Ad‐
       ditionally,  the  bitmapped, monospaced Courier and Elite typefaces are
       available in regular, bold, and italic styles;  Courier  at  8  and  12
       points,  Elite  at 8 and 10 points.  The following chart summarizes the
       groff font names used to access them.

           ┌───────────────┬─────────┬────────┬──────────┬──────────────┐
           │   Typeface    │  Roman  │  Bold  │  Italic  │  Bold‐Italic │
           ├───────────────┼─────────┼────────┼──────────┼──────────────┤
           │ Dutch         │  TR     │  TB    │  TI      │  TBI         │
           ├───────────────┼─────────┼────────┼──────────┼──────────────┤
           │ Swiss         │  HR     │  HB    │  HI      │  HBI         │
           ├───────────────┼─────────┼────────┼──────────┼──────────────┤
           │ Swiss Narrow  │  HNR    │  HNB   │  HNI     │  HNBI        │
           ├───────────────┼─────────┼────────┼──────────┼──────────────┤
           │ Courier       │  CR     │  CB    │  CI      │              │
           ├───────────────┼─────────┼────────┼──────────┼──────────────┤
           │ Elite         │  ER     │  EB    │  EI      │              │
           └───────────────┴─────────┴────────┴──────────┴──────────────┘

   Paper format, orientation, and device description file
       grolbp supports paper formats “A4”, “letter”, “legal”, and “executive”.
       These are matched case‐insensitively.  The -p, --papersize option over‐
       rides any setting in the device  description  file  DESC.   If  neither
       specifies a paper format, A4 is assumed.

       In its DESC file, grolbp (case‐insensitively) recognizes an orientation
       directive accepting one mandatory argument, portrait or landscape.  The
       first  valid  orientation  directive encountered controls.  The -l, -o,
       and --orientation command‐line options override any  setting  in  DESC.
       If none of the foregoing specify the orientation, portrait is assumed.

   Font description files
       In  addition  to  the  font  description  file directives documented in
       groff_font(5), grolbp recognizes lbpname, which  maps  the  groff  font
       name to the font name used internally by the printer.  Its syntax is as
       follows.
              lbpname printer‐font‐name
       lbpname’s argument is case‐sensitive.  The printer’s font names are en‐
       coded as follows.

       For bitmapped fonts, printer‐font_name has the form
              N⟨base‐font‐name⟩⟨font‐style⟩
       base‐font‐name  is  the  font  name as it appears in the printer’s font
       listings without the first letter, up to (but not including)  the  font
       size.   font‐style can be one of the letters R, I, or B, indicating the
       roman, italic, and bold styles, respectively.   For  instance,  if  the
       printer’s “font listing A” shows “Nelite12I.ISO_USA”, the corresponding
       entry in the groff font description file is
              lbpname NeliteI
       You  may  need to modify grolbp to add support for new bitmapped fonts,
       since the available font names and font sizes of  bitmapped  fonts  (as
       documented above) are hard‐coded into the program.

       For  scalable fonts, printer‐font‐name is identical to the font name as
       it appears in the printer’s “font listing A”.  For instance, to  select
       the  “Swiss” font in bold‐italic style, which appears in the font list‐
       ing as “Swiss-BoldOblique”,
              lbpname Swiss-BoldOblique
       is the required directive, and this is what we find in the  groff  font
       description file HBI for the lbp device.

   Drawing commands
       For  compatibility  with  grolj4(1),  an  additional drawing command is
       available.

       \D'R dh dv'
              Draw a rule (solid black rectangle) with one corner at the draw‐
              ing position, and the diagonally opposite corner at the  drawing
              position +(dh,dv).

Options
       -h and --help display a usage message, while -v and --version show ver‐
       sion information; all exit afterward.

       -c num‐copies
       --copies=num‐copies
              Produce num‐copies copies of each page.

       -F font‐directory
       --fontdir=font‐directory
              Prepend  directory font‐directory/devname to the search path for
              font and device description files; name is the name of  the  de‐
              vice, usually lbp.

       -l
       --landscape
              Format the document in landscape orientation.

       -o orientation
       --orientation=orientation
              Format  the  document  in  the  given orientation, which must be
              “portrait” or “landscape”.

       -p paper‐format
       --papersize=paper‐format
              Set the paper format to paper‐format, which must be a valid  pa‐
              per format as described above.

       -w width
       --linewidth=width
              Set  the  default  line thickness to width thousandths of an em;
              the default is 40 (0.04 em).

Environment
       GROFF_FONT_PATH
              lists directories in which to seek the selected output  device’s
              directory  of  device  and font description files.  See troff(1)
              and groff_font(5).

Files
       /usr/share/groff/1.23.0/font/devlbp/DESC
              describes the lbp output device.

       /usr/share/groff/1.23.0/font/devlbp/F
              describes the font known as F on device lbp.

       /usr/share/groff/1.23.0/tmac/lbp.tmac
              defines macros for use with the lbp output device.  It is  auto‐
              matically  loaded  by  troffrc when the lbp output device is se‐
              lected.

See also
       groff(1), troff(1), groff_out(5), groff_font(5), groff_char(7)

groff 1.23.0                      2 July 2023                        grolbp(1)
───────────────────────────────────────────────────────────────────────────────
grolj4(1)                   General Commands Manual                  grolj4(1)

Name
       grolj4 - groff output driver for HP LaserJet 4 and compatible printers

Synopsis
       grolj4 [-l] [-c num‐copies] [-d [n]] [-F font‐directory] [-p paper‐
              format] [-w line‐width] [file ...]

       grolj4 --help

       grolj4 -v
       grolj4 --version

Description
       This GNU roff output driver translates the output of  troff(1)  into  a
       PCL5 format suitable for an HP LaserJet 4 printer.  Normally, grolj4 is
       invoked  by groff(1) when the latter is given the “-T lj4” option.  (In
       this installation, ps is the default output device.)   Use  groff’s  -P
       option to pass any options shown above to grolj4.  If no file arguments
       are  given,  or if file is “-”, grolj4 reads the standard input stream.
       Output is written to the standard output stream.

   Typefaces
       grolj4 supports the standard four styles:  R  (roman),  I  (italic),  B
       (bold), and BI (bold‐italic).  Fonts are grouped into families A, C, G,
       O, T, TN, U, and UC having members in each style.

              AB            Arial Bold
              ABI           Arial Bold Italic
              AI            Arial Italic
              AR            Arial Roman
              CB            Courier Bold
              CBI           Courier Bold Italic
              CI            Courier Italic
              CR            Courier Roman
              GB            Garamond Halbfett
              GBI           Garamond Kursiv Halbfett
              GI            Garamond Kursiv
              GR            Garamond Antiqua
              OB            CG Omega Bold
              OBI           CG Omega Bold Italic
              OI            CG Omega Italic
              OR            CG Omega Roman
              OB            CG Omega Bold
              OBI           CG Omega Bold Italic
              OI            CG Omega Italic
              OR            CG Omega Roman
              TB            CG Times Bold
              TBI           CG Times Bold Italic
              TI            CG Times Italic
              TR            CG Times Roman
              TNRB          M Times Bold
              TNRBI         M Times Bold Italic
              TNRI          M Times Italic
              TNRR          M Times Roman
              UB            Univers Bold
              UBI           Univers Bold Italic
              UI            Univers Medium Italic
              UR            Univers Medium
              UCB           Univers Condensed Bold
              UCBI          Univers Condensed Bold Italic
              UCI           Univers Condensed Medium Italic
              UCR           Univers Condensed Medium

       The following fonts are not members of a family.

              ALBB          Albertus Extra Bold
              ALBR          Albertus Medium
              AOB           Antique Olive Bold
              AOI           Antique Olive Italic
              AOR           Antique Olive Roman
              CLARENDON     Clarendon
              CORONET       Coronet
              LGB           Letter Gothic Bold
              LGI           Letter Gothic Italic
              LGR           Letter Gothic Roman
              MARIGOLD      Marigold

       The  special  font  is  S  (PostScript  Symbol); SYMBOL (M Symbol), and
       WINGDINGS (Wingdings) are also available but not mounted by default.

   Paper format and device description file
       grolj4  supports  paper  formats  “A4”,  “B5”,  “C5”,  “com10”,   “DL”,
       “executive”, “legal”, “letter”, and “monarch”.  These are matched case‐
       insensitively.   The  -p option overrides any setting in the device de‐
       scription file DESC.  If neither specifies a paper format, “letter”  is
       assumed.

   Font description files
       grolj4  recognizes four font description file directives in addition to
       those documented in groff_font(5).

       pclweight n
              Set the stroke weight to n, an integer in the range  -7  to  +7;
              the default is 0.

       pclstyle n
              Set  the style to n, an integer in the range 0 to 32767; the de‐
              fault is 0.

       pclproportional n
              Set the proportional spacing Boolean flag to n, which can be ei‐
              ther 0 or 1; the default is 0.

       pcltypeface n
              Set the typeface family to n, an  integer  in  the  range  0  to
              65535; the default is 0.

   Drawing commands
       An  additional  drawing  command is recognized as an extension to those
       documented in groff(7).

       \D'R dh dv'
              Draw a rule (solid black rectangle) with one corner at the draw‐
              ing position, and the diagonally opposite corner at the  drawing
              position  +(dh,dv), at which the drawing position will be after‐
              ward.  This generates a PCL fill rectangle command, and so  will
              work  on  printers that do not support HP‐GL/2, unlike the other
              \D commands.

   Fonts
       Nominally, all Hewlett‐Packard LaserJet  4‐series  and  newer  printers
       have  the  same  internal  fonts:  45  scalable fonts and one bitmapped
       Lineprinter font.  The scalable fonts are available  in  sizes  between
       0.25   points   and   999.75  points,  in  0.25‐point  increments;  the
       Lineprinter font is available only in 8.5‐point size.

       The LaserJet font files included with groff assume  that  all  printers
       since the LaserJet 4 are identical.  There are some differences between
       fonts in the earlier and more recent printers, however.  The LaserJet 4
       printer  used  Agfa Intellifont technology for 35 of the internal scal‐
       able fonts; the remaining 10 scalable fonts were  TrueType.   Beginning
       with the LaserJet 4000‐series printers introduced in 1997, all scalable
       internal fonts have been TrueType.  The number of printable glyphs dif‐
       fers  slightly  between  Intellifont and TrueType fonts (generally, the
       TrueType fonts include more glyphs), and there are some  minor  differ‐
       ences in glyph metrics.  Differences among printer models are described
       in  the  PCL 5 Comparison Guide and the PCL 5 Comparison Guide Addendum
       (for printers introduced since approximately 2001).

       LaserJet printers reference a glyph by a  combination  of  a  256‐glyph
       symbol  set and an index within that symbol set.  Many glyphs appear in
       more than one symbol set; all combinations of symbol set and index that
       reference the same glyph are equivalent.  For each  glyph,  hpftodit(1)
       searches a list of symbol sets, and selects the first set that contains
       the  glyph.  The printing code generated by hpftodit is an integer that
       encodes a numerical value for the symbol set in the high  byte(s),  and
       the  index  in the low byte.  See groff_font(5) for a complete descrip‐
       tion of the font file format; symbol sets are described in greater  de‐
       tail in the PCL 5 Printer Language Technical Reference Manual.

       Two of the scalable fonts, Symbol and Wingdings, are bound to 256‐glyph
       symbol  sets;  the remaining scalable fonts, as well as the Lineprinter
       font, support numerous symbol sets, sufficient to  enable  printing  of
       more than 600 glyphs.

       The  metrics  generated  by hpftodit assume that the DESC file contains
       values of 1200 for res and  6350  for  unitwidth,  or  any  combination
       (e.g., 2400 and 3175) for which res × unitwidth = 7620000.  Although HP
       PCL  5  LaserJet  printers support an internal resolution of 7200 units
       per inch, they use a 16‐bit signed integer for positioning;  if  devlj4
       is to support U.S. ledger paper (11 in × 17 in; in = inch), the maximum
       usable  resolution  is 32767 ÷ 17, or 1927 units per inch, which rounds
       down to 1200 units per inch.  If the largest required  paper  dimension
       is  less  (e.g.,  8.5  in  ×  11  in, or A5), a greater res (and lesser
       unitwidth) can be specified.

       Font metrics for Intellifont fonts were provided by Tagged Font  Metric
       (TFM)  files  originally developed by Agfa/Compugraphic.  The TFM files
       provided for these fonts supported 600+ glyphs and contained  extensive
       lists of kerning pairs.

       To  accommodate  developers  who had become accustomed to TFM files, HP
       also provided TFM files for the  10  TrueType  fonts  included  in  the
       LaserJet  4.   The TFM files for TrueType fonts generally included less
       information than the Intellifont TFMs, supporting fewer glyphs, and  in
       most  cases,  providing no kerning information.  By the time the Laser‐
       Jet 4000 printer was introduced, most developers had migrated to  other
       means of obtaining font metrics, and support for new TFM files was very
       limited.   The  TFM files provided for the TrueType fonts in the Laser‐
       Jet 4000 support only the Latin 2 (ISO 8859‐2) symbol set, and  include
       no  kerning information; consequently, they are of little value for any
       but the most rudimentary documents.

       Because the Intellifont TFM files contain  considerably  more  informa‐
       tion,  they generally are preferable to the TrueType TFM files even for
       use with the TrueType fonts in the newer printers.  The metrics for the
       TrueType fonts are very close, though not identical, to those  for  the
       earlier  Intellifont fonts of the same names.  Although most output us‐
       ing the Intellifont metrics with the newer printers  is  quite  accept‐
       able,  a  few glyphs may fail to print as expected.  The differences in
       glyph metrics may be particularly noticeable with  composite  parenthe‐
       ses,  brackets,  and braces used by eqn(1).  A script, located in /usr/
       share/groff/1.23.0/font/devlj4/generate, can be used to adjust the met‐
       rics for these glyphs in the special font “S”  for  use  with  printers
       that have all TrueType fonts.

       At  the  time HP last supported TFM files, only version 1.0 of the Uni‐
       code standard was available.  Consequently,  many  glyphs  lacking  as‐
       signed  code  points were assigned by HP to the Private Use Area (PUA).
       Later versions of the Unicode standard included code points outside the
       PUA for many of these glyphs.  The HP‐supplied TrueType TFM  files  use
       the PUA assignments; TFM files generated from more recent TrueType font
       files require the later Unicode values to access the same glyphs.  Con‐
       sequently, two different mapping files may be required: one for the HP‐
       supplied TFM files, and one for more recent TFM files.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -c num‐copies
              Format num‐copies copies of each page.

       -d [n] Use duplex mode n: 1 is long‐side binding (default),  and  2  is
              short‐side binding.

       -F font‐directory
              Prepend  directory font‐directory/devname to the search path for
              font and device description files; name is the name of  the  de‐
              vice, usually lj4.

       -l     Format the document in landscape orientation.

       -p paper‐format
              Set  the paper format to paper‐format, which must be a valid pa‐
              per format as described above.

       -w line‐width
              Set the default line thickness to line‐width thousandths  of  an
              em; the default is 40 (0.04 em).

Environment
       GROFF_FONT_PATH
              lists  directories in which to seek the selected output device’s
              directory of device and font description  files.   See  troff(1)
              and groff_font(5).

Files
       /usr/share/groff/1.23.0/font/devlj4/DESC
              describes the lj4 output device.

       /usr/share/groff/1.23.0/font/devlj4/F
              describes the font known as F on device lj4.

       /usr/share/groff/1.23.0/tmac/lj4.tmac
              defines  macros for use with the lj4 output device.  It is auto‐
              matically loaded by troffrc when the lj4 output  device  is  se‐
              lected.

Bugs
       Small dots.

See also
       HP  PCL/PJL  Reference: PCL 5 Printer Language Technical Reference Man‐
       ual, Part I ⟨http://www.hp.com/ctg/Manual/bpl13210.pdf⟩

       hpftodit(1),   groff(1),   troff(1),    groff_out(5),    groff_font(5),
       groff_char(7)

groff 1.23.0                      2 July 2023                        grolj4(1)
───────────────────────────────────────────────────────────────────────────────
gropdf(1)                   General Commands Manual                  gropdf(1)

Name
       gropdf - groff output driver for Portable Document Format

Synopsis
       gropdf [-dels] [-F font‐directory] [-I inclusion‐directory] [-p paper‐
              format] [-u [cmap‐file]] [-y foundry] [file ...]

       gropdf --help

       gropdf -v
       gropdf --version

Description
       The  GNU  roff PDF output driver translates the output of troff(1) into
       Portable Document Format.  Normally, gropdf is invoked by groff(1) when
       the latter is given the “-T pdf” option.  (In this installation, ps  is
       the  default output device.)  Use groff’s -P option to pass any options
       shown above to gropdf.  If no file arguments are given, or if  file  is
       “-”,  gropdf reads the standard input stream.  Output is written to the
       standard output stream.

       See section “Font installation” below for a guide to  installing  fonts
       for gropdf.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -d     Include debug information as comments within the PDF.  Also pro‐
              duces an uncompressed PDF.

       -e     Forces gropdf to embed all fonts (even the 14 base PDF fonts).

       -F dir Prepend directory dir/devname to the search path for  font,  and
              device  description  files; name is the name of the device, usu‐
              ally pdf.

       -I dir Search the directory dir for files named in \X'pdf: pdfpic'  de‐
              vice control commands.  -I may be specified more than once; each
              dir is searched in the given order.  To search the current work‐
              ing directory before others, add “-I .” at the desired place; it
              is otherwise searched last.

       -l     Orient the document in landscape format.

       -p paper‐format
              Set  the  physical  dimensions of the output medium.  This over‐
              rides the papersize, paperlength, and paperwidth  directives  in
              the  DESC  file;  it accepts the same arguments as the papersize
              directive.  See groff_font(5) for details.

       -s     Append a comment line to end of  PDF  showing  statistics,  i.e.
              number  of  pages  in  document.  Ghostscript’s ps2pdf complains
              about this line if it is included, but works anyway.

       -u [cmap‐file]
              gropdf normally includes a ToUnicode CMap with any font  created
              using  text.enc  as  the  encoding file, this makes it easier to
              search for words which contain ligatures.  You can include  your
              own  CMap  by  specifying  a cmap‐file or have no CMap at all by
              omitting the argument.

       -y foundry
              Set the foundry to use for selecting fonts of the same name.

Usage
       The input to gropdf must be in the format output by troff(1).  This  is
       described  in  groff_out(5).  In addition, the device and font descrip‐
       tion files for the device used must meet certain requirements: The res‐
       olution must be an integer multiple of 72 times the sizescale.  The pdf
       device uses a resolution of 72000 and a sizescale of 1000.

       The device description file must contain  a  valid  paper  format;  see
       groff_font(5).   gropdf  uses the same Type 1 Adobe PostScript fonts as
       the grops device driver.  Although the PDF Standard allows the  use  of
       other  font  types (like TrueType) this implementation only accepts the
       Type 1 PostScript font.  Fewer Type 1 fonts are supported  natively  in
       PDF  documents  than  the  standard 35 fonts supported by grops and all
       PostScript printers, but all the fonts are available  since  any  which
       aren’t supported natively are automatically embedded in the PDF.

       gropdf supports the concept of foundries, that is different versions of
       basically  the same font.  During install a Foundry file controls where
       fonts are found and builds groff fonts from the files it  discovers  on
       your system.

       Each font description file must contain a command

              internalname psname

       which  says  that  the  PostScript  name  of the font is psname.  Lines
       starting with # and blank lines are ignored.  The code for each charac‐
       ter given in the font file must correspond to the code in  the  default
       encoding  for  the  font.  This code can be used with the \N escape se‐
       quence in troff to select the character, even if the character does not
       have a groff name.  Every character in the font file must exist in  the
       PostScript  font,  and the widths given in the font file must match the
       widths used in the PostScript font.

       Note that gropdf is currently only able to display the first 256 glyphs
       in any font.  This restriction will be lifted in a later version.

       gropdf can automatically include the downloadable  fonts  necessary  to
       print the document.  Fonts may be in PFA or PFB format.

       Any  downloadable  fonts  which  should,  when required, be included by
       gropdf must be listed in the file  /usr/share/groff/1.23.0/font/devpdf/
       download; this should consist of lines of the form

              foundry font filename

       where  foundry  is  the  foundry name or blank for the default foundry.
       font is the PostScript name of the font, and filename is  the  name  of
       the  file  containing  the font; lines beginning with # and blank lines
       are ignored; fields must be separated by tabs (spaces are not allowed);
       filename is searched for using the same  mechanism  that  is  used  for
       groff font metric files.  The download file itself is also sought using
       this  mechanism.  Foundry names are usually a single character (such as
       ‘U’ for the URW foundry) or empty for the default  foundry.   This  de‐
       fault uses the same fonts as ghostscript uses when it embeds fonts in a
       PDF file.

       In the default setup there are styles called R, I, B, and BI mounted at
       font  positions  1 to 4.  The fonts are grouped into families A, BM, C,
       H, HN, N, P, and T having members in each of these styles:

              AR     AvantGarde‐Book
              AI     AvantGarde‐BookOblique
              AB     AvantGarde‐Demi
              ABI    AvantGarde‐DemiOblique
              BMR    Bookman‐Light
              BMI    Bookman‐LightItalic
              BMB    Bookman‐Demi
              BMBI   Bookman‐DemiItalic
              CR     Courier
              CI     Courier‐Oblique
              CB     Courier‐Bold
              CBI    Courier‐BoldOblique
              HR     Helvetica
              HI     Helvetica‐Oblique
              HB     Helvetica‐Bold
              HBI    Helvetica‐BoldOblique
              HNR    Helvetica‐Narrow
              HNI    Helvetica‐Narrow‐Oblique
              HNB    Helvetica‐Narrow‐Bold
              HNBI   Helvetica‐Narrow‐BoldOblique
              NR     NewCenturySchlbk‐Roman
              NI     NewCenturySchlbk‐Italic
              NB     NewCenturySchlbk‐Bold
              NBI    NewCenturySchlbk‐BoldItalic
              PR     Palatino‐Roman
              PI     Palatino‐Italic
              PB     Palatino‐Bold
              PBI    Palatino‐BoldItalic
              TR     Times‐Roman
              TI     Times‐Italic
              TB     Times‐Bold
              TBI    Times‐BoldItalic

       There is also the following font which is not a member of a family:

              ZCMI   ZapfChancery‐MediumItalic

       There are also some special fonts called S for the PS Symbol font.  The
       lower case greek characters are automatically  slanted  (to  match  the
       SymbolSlanted  font  (SS)  available  to PostScript).  Zapf Dingbats is
       available as ZD; the “hand pointing left” glyph  (\[lh])  is  available
       since  it  has been defined using the \X'pdf: xrev' device control com‐
       mand, which reverses the direction of letters within words.

       The default color for \m and \M is black.

       gropdf understands some of the device  control  commands  supported  by
       grops(1).

       \X'ps: invis'
              Suppress output.

       \X'ps: endinvis'
              Stop suppressing output.

       \X'ps: exec gsave currentpoint 2 copy translate n rotate neg exch neg
       exch translate'
              where  n is the angle of rotation.  This is to support the align
              command in pic(1).

       \X'ps: exec grestore'
              Used by pic(1) to restore state after rotation.

       \X'ps: exec n setlinejoin'
              where n can be one of the following values.

              0 = Miter join
              1 = Round join
              2 = Bevel join

       \X'ps: exec n setlinecap'
              where n can be one of the following values.

              0 = Butt cap
              1 = Round cap, and
              2 = Projecting square cap

       \X'ps: ... pdfmark'
              All the pdfmark macros installed by using -m pdfmark or -m mspdf
              (see documentation in pdfmark.pdf).  A subset  of  these  macros
              are installed automatically when you use -Tpdf so you should not
              need to use “-m pdfmark” to access most PDF functionality.

       gropdf   also   supports   a  subset  of  the  commands  introduced  in
       present.tmac.  Specifically it supports:‐

              PAUSE
              BLOCKS
              BLOCKE

       Which allows you to create presentation type PDFs.  Many of  the  other
       commands are already available in other macro packages.

       These commands are implemented with groff X commands:‐

       \X'ps: exec %%%%PAUSE'
              The  section before this is treated as a block and is introduced
              using the current BLOCK transition setting (see “\X'pdf: transi‐
              tion'” below).  Equivalently, .pdfpause is available as a macro.

       \X'ps: exec %%%%BEGINONCE'
              Any text following this command (up  to  %%%%ENDONCE)  is  shown
              only  once,  the  next %%%%PAUSE will remove it.  If producing a
              non‐presentation   PDF,   i.e.   ignoring   the   pauses,    see
              GROPDF_NOSLIDE below, this text is ignored.

       \X'ps: exec %%%%ENDONCE'
              This  terminates  the block defined by %%%%BEGINONCE.  This pair
              of commands is what implements the .BLOCKS Once/.BLOCKE commands
              in present.tmac.

       The mom macro package already integrates these extensions, so  you  can
       build slides with mom.

       If you use present.tmac with gropdf there is no need to run the program
       presentps(1) since the output will already be a presentation PDF.

       All other ps: tags are silently ignored.

       One  \X  device  control  command used by the DVI driver is also recog‐
       nised.

       \X'papersize=paper‐format'
              where the paper‐format parameter is the same as that to the  pa‐
              persize  directive.  See groff_font(5).  This means that you can
              alter the page size at will within the PDF file being created by
              gropdf.  If you do want to change the paper format, it  must  be
              done before you start creating the page.

       gropdf  supports  several  more  device control features using the pdf:
       tag.  Some have counterpart convenience macros that take the same argu‐
       ments and behave equivalently.

       \X'pdf: pdfpic file alignment width height line‐length'
              Place an image of the specified width containing the PDF drawing
              from file file of desired width and height (if height is missing
              or zero then it is scaled proportionally).  If alignment  is  -L
              the  drawing  is  left‐aligned.  If it is -C or -R a line‐length
              greater than the width of the drawing is required as  well.   If
              width  is  specified as zero then the width is scaled in propor‐
              tion to the height.

       \X'pdf: xrev'
              Toggle the reversal of  glyph  direction.   This  feature  works
              “letter  by  letter”, that is, each letter in a word is reversed
              left‐to‐right, not the entire word.  One application is the  re‐
              versal of glyphs in the Zapf Dingbats font.  To restore the nor‐
              mal glyph orientation, repeat the command.

       \X'pdf: markstart /ANN‐definition'
       \X'pdf: markend'
              Macros  that support PDF bookmarks use these calls internally to
              start and stop (respectively) the placement  of  the  bookmark’s
              hot  spot;  the user will have called “.pdfhref L” with the text
              of the hot spot.  Normally, these are  never  used  except  from
              within the pdfmark macros.

       \X'pdf: marksuspend'
       \X'pdf: markrestart'
              If  you  use a page location trap to produce a header or footer,
              or otherwise interrupt a document’s text, you need to use  these
              commands  if  a  PDF hot spot crosses a trap boundary; otherwise
              any text output by the trap will be marked as part  of  the  hot
              spot.   To  prevent  this error, place these device control com‐
              mands or their corresponding convenience macros  .pdfmarksuspend
              and  .pdfmarkrestart at the start and end of the trap macro, re‐
              spectively.

       \X'pdf: pagename name'
              Assign the current page a name.  All documents bear two  default
              names,  ‘top’ and ‘bottom’.  The convenience macro for this com‐
              mand is .pdfpagename.

       \X’pdf: switchtopage when name'
              Normally each new page is appended to the end of  the  document,
              this  command allows following pages to be inserted at a ‘named’
              position within  the  document  (see  pagename  command  above).
              ‘when’  can  be either ‘after’ or ‘before’.  If it is omitted it
              defaults to ‘before’.  It should be used at the end of the  page
              before you want the switch to happen.  This allows pages such as
              a  TOC  to  be moved to elsewhere in the document, but more eso‐
              teric uses are possible.  The convenience macro for this command
              is .pdfswitchtopage.

       \X'pdf: transition feature mode duration dimension motion direction
       scale bool'
              where feature can be either SLIDE or BLOCK.  When  it  is  SLIDE
              the  transition  is  used  when a new slide is introduced to the
              screen, if BLOCK then this transition is used for the individual
              blocks which make up the slide.

              mode is the transition type between slides:‐

                     Split ‐ Two lines sweep across the screen, revealing  the
                     new page.  The lines may be either horizontal or vertical
                     and may move inward from the edges of the page or outward
                     from the center, as specified by the dimension and motion
                     entries, respectively.
                     Blinds ‐ Multiple lines, evenly spaced across the screen,
                     synchronously  sweep  in the same direction to reveal the
                     new page.  The lines may be either horizontal  or  verti‐
                     cal,  as  specified  by  the dimension entry.  Horizontal
                     lines move downward; vertical lines move to the right.
                     Box ‐ A rectangular box sweeps inward from the  edges  of
                     the  page or outward from the center, as specified by the
                     motion entry, revealing the new page.
                     Wipe ‐ A single line sweeps across the  screen  from  one
                     edge  to  the other in the direction specified by the di‐
                     rection entry, revealing the new page.
                     Dissolve ‐ The old page dissolves gradually to reveal the
                     new one.
                     Glitter ‐ Similar to Dissolve,  except  that  the  effect
                     sweeps  across  the  page  in a wide band moving from one
                     side of the screen to the other in the  direction  speci‐
                     fied by the direction entry.
                     R ‐ The new page simply replaces the old one with no spe‐
                     cial  transition effect; the direction entry shall be ig‐
                     nored.
                     Fly ‐ (PDF 1.5) Changes are flown out or in (as specified
                     by motion), in the direction specified by  direction,  to
                     or  from  a location that is offscreen except when direc‐
                     tion is None.
                     Push ‐ (PDF 1.5) The old page slides off the screen while
                     the new page slides in, pushing the old page out  in  the
                     direction specified by direction.
                     Cover ‐ (PDF 1.5) The new page slides on to the screen in
                     the  direction  specified  by direction, covering the old
                     page.
                     Uncover ‐ (PDF 1.5) The old page slides off the screen in
                     the direction specified by direction, uncovering the  new
                     page in the direction specified by direction.
                     Fade  ‐  (PDF 1.5) The new page gradually becomes visible
                     through the old one.

              duration is the length of the transition in seconds (default 1).

              dimension (Optional; Split and Blinds  transition  styles  only)
              The dimension in which the specified transition effect shall oc‐
              cur: H Horizontal, or V Vertical.

              motion (Optional; Split, Box and Fly transition styles only) The
              direction  of  motion for the specified transition effect: I In‐
              ward from the edges of the page, or O Outward from the center of
              the page.

              direction (Optional; Wipe, Glitter, Fly, Cover, Uncover and Push
              transition styles only) The direction  in  which  the  specified
              transition  effect  shall  moves,  expressed in degrees counter‐
              clockwise starting from a left‐to‐right direction.  If the value
              is a number, it shall be one of: 0 = Left to right, 90 =  Bottom
              to  top  (Wipe only), 180 = Right to left (Wipe only), 270 = Top
              to bottom, 315 = Top‐left to  bottom‐right  (Glitter  only)  The
              value can be None, which is relevant only for the Fly transition
              when the value of scale is not 1.0.

              scale  (Optional; PDF 1.5; Fly transition style only) The start‐
              ing or ending scale at which the changes shall be drawn.  If mo‐
              tion specifies an inward transition, the scale  of  the  changes
              drawn  shall  progress  from scale to 1.0 over the course of the
              transition.  If motion  specifies  an  outward  transition,  the
              scale of the changes drawn shall progress from 1.0 to scale over
              the course of the transition

              bool (Optional; PDF 1.5; Fly transition style only) If true, the
              area that shall be flown in is rectangular and opaque.

              This command can be used by calling the macro .pdftransition us‐
              ing  the  parameters described above.  Any of the parameters may
              be replaced with a "." which signifies the parameter retains its
              previous value, also any trailing  missing  parameters  are  ig‐
              nored.

              Note: not all PDF Readers support any or all these transitions.

       \X'pdf: background cmd left top right bottom weight'
       \X'pdf: background off'
       \X'pdf: background footnote bottom'
              produces a background rectangle on the page, where

              cmd    is  the  command,  which can be any of “page|fill|box” in
                     combination.  Thus, “pagefill”  would  draw  a  rectangle
                     which  covers  the whole current page size (in which case
                     the rest of the parameters can be omitted because the box
                     dimensions are taken from the current media size).  “box‐
                     fill”, on the other hand, requires the  given  dimensions
                     to  place  the box.  Including “fill” in the command will
                     paint the rectangle with the current fill colour (as with
                     \M[]) and including “box” will give the rectangle a  bor‐
                     der in the current stroke colour (as with \m[]).

                     cmd  may  also  be “off” on its own, which will terminate
                     drawing the current box.  If you have  specified  a  page
                     colour with “pagefill”, it is always the first box in the
                     stack,  and  if you specify it again, it will replace the
                     first entry.  Be aware that the  “pagefill”  box  renders
                     the  page opaque, so tools that “watermark” PDF pages are
                     unlikely to be successful.  To return the  background  to
                     transparent,  issue  an “off” command with no other boxes
                     open.

                     Finally, cmd may be “footnote” followed by  a  new  value
                     for  bottom, which will be used for all open boxes on the
                     current page.  This is to allow room for  footnote  areas
                     that  grow while a page is processed (to accommodate mul‐
                     tiple footnotes, for instance).  (If the value  is  nega‐
                     tive,  it  is  used  as  an offset from the bottom of the
                     page.)

              left
              top
              right
              bottom are the coordinates of the box.  The top and bottom coor‐
                     dinates are the minimum and maximum for  the  box,  since
                     the  actual  start of the box is groff’s drawing position
                     when you issue the command, and the bottom of the box  is
                     the point where you turn the box “off”.  The top and bot‐
                     tom  coordinates are used only if the box drawing extends
                     onto the next page; ordinarily, they would be set to  the
                     header and footer margins.

              weight provides  the  line  width for the border if “box” is in‐
                     cluded in the command.

              The convenience macro for  this  escape  sequence  is  .pdfback‐
              ground.    An   sboxes   macro   file  is  also  available;  see
              groff_tmac(5).

   Macros
       gropdf’s support macros in pdf.tmac define the convenience  macros  de‐
       scribed  above.   Some  features  have no direct device control command
       counterpart.

       .pdfinfo /field content ...
              Define PDF metadata.  field may be be one of Title, Author, Sub‐
              ject, Keywords, or another datum supported by the  PDF  standard
              or your reader.  field must be prefixed with a slash.

   Importing graphics
       gropdf  supports  only  the inclusion of other PDF files for inline im‐
       ages.  Such a PDF file may, however, contain any of the graphic formats
       supported by the PDF standard, such as JPEG/JFIF, PNG,  and  GIF.   Any
       application  that outputs PDF can thus be used to prepare files for em‐
       bedding in documents processed by groff and gropdf.

       The PDF file you wish to insert must be a single page and  the  drawing
       must just fit inside the media size of the PDF file.  In inkscape(1) or
       gimp(1), for example, make sure the canvas size just fits the image.

       The  PDF  parser  gropdf implements has not been rigorously tested with
       all applications that produce PDF.  If you find a single‐page PDF which
       fails to import properly, try processing it with the pdftk(1) program.
              pdftk existing‐file output new‐file
       You may find that new‐file imports successfully.

   TrueType and other font formats
       gropdf does not yet support any font formats besides Adobe Type 1  (PFA
       or PFB).

Font installation
       The following is a step‐by‐step font installation guide for gropdf.

       • Convert  your  font  to something groff understands.  This is a Post‐
         Script Type 1 font in PFA or PFB format, together with an  AFM  file.
         A PFA file begins as follows.
                %!PS-AdobeFont-1.0:
         A  PFB file contains this string as well, preceded by some non‐print‐
         ing bytes.  In the following steps,  we  will  consider  the  use  of
         CTAN’s    BrushScriptX‐Italic    ⟨https://ctan.org/tex-archive/fonts/
         brushscr⟩ font in PFA format.

       • Convert the AFM file to  a  groff  font  description  file  with  the
         afmtodit(1) program.  For instance,
                $ afmtodit BrushScriptX-Italic.afm text.map BSI
         converts  the  Adobe  Font Metric file BrushScriptX-Italic.afm to the
         groff font description file BSI.

         If you have a font family which  provides  regular  upright  (roman),
         bold,   italic,  and  bold‐italic  styles,  (where  “italic”  may  be
         “oblique” or “slanted”), we recommend using R, B, I, and BI,  respec‐
         tively,  as  suffixes to the groff font family name to enable groff’s
         font family and style selection  features.   An  example  is  groff’s
         built‐in support for Times: the font family name is abbreviated as T,
         and  the  groff font names are therefore TR, TB, TI, and TBI.  In our
         example, however, the BrushScriptX font  is  available  in  a  single
         style only, italic.

       • Install  the  groff font description file(s) in a devpdf subdirectory
         in the search path that groff uses for device and font file  descrip‐
         tions.   See  the  GROFF_FONT_PATH  entry in section “Environment” of
         troff(1) for the current value of the font search path.  While  groff
         doesn’t  directly  use  AFM  files,  it  is a good idea to store them
         alongside its font description files.

       • Register fonts in the devpdf/download file so they can be located for
         embedding in PDF files gropdf generates.   Only  the  first  download
         file  encountered in the font search path is read.  If in doubt, copy
         the default download file (see section “Files” below)  to  the  first
         directory  in  the  font  search  path and add your fonts there.  The
         PostScript font name used by gropdf is  stored  in  the  internalname
         field in the groff font description file.  (This name does not neces‐
         sarily  resemble  the  font’s file name.)  If the font in our example
         had originated from a foundry named Z, we  would  add  the  following
         line to download.
                Z→BrushScriptX-Italic→BrushScriptX-Italic.pfa
         A  tab  character,  depicted as →, separates the fields.  The default
         foundry has no name: its field is empty and entries corresponding  to
         it start with a tab character, as will the one in our example.

       • Test the selection and embedding of the new font.
                printf "\\f[BSI]Hello, world!\n" | groff -T pdf -P -e >hello.pdf
                see hello.pdf

Environment
       GROFF_FONT_PATH
              A  list  of directories in which to seek the selected output de‐
              vice’s directory of device and font description files.   If,  in
              the  download file, the font file has been specified with a full
              path,  no  directories   are   searched.    See   troff(1)   and
              groff_font(5).

       GROPDF_NOSLIDE
              If  set  and evaluates to a true value (to Perl), gropdf ignores
              commands specific to presentation PDFs, producing a  normal  PDF
              instead.

       SOURCE_DATE_EPOCH
              A  timestamp  (expressed as seconds since the Unix epoch) to use
              as the output creation timestamp in place of the  current  time.
              The  time  is  converted  to  human‐readable  form  using Perl’s
              localtime() function and recorded in a PDF comment.

       TZ     The time zone to use when converting the current time (or  value
              of SOURCE_DATE_EPOCH) to human‐readable form; see tzset(3).

Files
       /usr/share/groff/1.23.0/font/devpdf/DESC
              describes the pdf output device.

       /usr/share/groff/1.23.0/font/devpdf/F
              describes the font known as F on device pdf.

       /usr/share/groff/1.23.0/font/devpdf/U-F
              describes  the  font  from the URW foundry (versus the Adobe de‐
              fault) known as F on device pdf.

       /usr/share/groff/1.23.0/font/devpdf/download
              lists fonts available for embedding within the PDF document  (by
              analogy to the ps device’s downloadable font support).

       /usr/share/groff/1.23.0/font/devpdf/Foundry
              is  a  data  file used by the groff build system to locate Post‐
              Script Type 1 fonts.

       /usr/share/groff/1.23.0/font/devpdf/enc/text.enc
              describes the encoding scheme used by  most  PostScript  Type  1
              fonts;  the encoding directive of font description files for the
              pdf device refers to it.

       /usr/share/groff/1.23.0/tmac/pdf.tmac
              defines macros for use with the pdf output device.  It is  auto‐
              matically  loaded  by  troffrc when the pdf output device is se‐
              lected.

       /usr/share/groff/1.23.0/tmac/pdfpic.tmac
              defines the PDFPIC macro for embedding images in a document; see
              groff_tmac(5).  It is automatically loaded by troffrc.

Authors
       gropdf was written and is maintained  by  Deri  James  ⟨deri@chuzzlewit
       .myzen.co.uk⟩.

See also
       /usr/share/doc/groff-1.23.0/sboxes/msboxes.ms
       /usr/share/doc/groff-1.23.0/sboxes/msboxes.pdf
              “Using PDF boxes with groff and the ms macros”, by Deri James.

       present.tmac
              is  part  of  gpresent  ⟨https://bob.diertens.org/corner/useful/
              gpresent/⟩, a software package by Bob Diertens that  works  with
              groff to produce presentations (“foils”, or “slide decks”).

       afmtodit(1), groff(1), troff(1), groff_font(5), groff_out(5)

groff 1.23.0                      2 July 2023                        gropdf(1)
───────────────────────────────────────────────────────────────────────────────
grops(1)                    General Commands Manual                   grops(1)

Name
       grops - groff output driver for PostScript

Synopsis
       grops [-glm] [-b brokenness‐flags] [-c num‐copies] [-F font‐directory]
             [-I inclusion‐directory] [-p paper‐format] [-P prologue‐file]
             [-w rule‐thickness] [file ...]

       grops --help

       grops -v
       grops --version

Description
       The GNU roff PostScript output driver translates the output of troff(1)
       into  PostScript.  Normally, grops is invoked by groff(1) when the lat‐
       ter is given the “-T ps” option.  (In this installation, ps is the  de‐
       fault  output device.)  Use groff’s -P option to pass any options shown
       above to grops.  If no file arguments are given, or  if  file  is  “-”,
       grotty reads the standard input stream.  Output is written to the stan‐
       dard output stream.

       When called with multiple file arguments, grops doesn’t produce a valid
       document  structure (one conforming to the Document Structuring Conven‐
       tions).  To print such concatenated output, it is necessary to  deacti‐
       vate DSC handling in the printing program or previewer.

       See  section  “Font installation” below for a guide to installing fonts
       for grops.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -b n   Work around problems with spoolers, previewers, and older print‐
              ers.     Normally,   grops   produces   output   at   PostScript
              LanguageLevel 2 that conforms to version  3.0  of  the  Document
              Structuring Conventions.  Some software and devices can’t handle
              such  a  data stream.  The value of n determines what grops does
              to make its output acceptable to such consumers.   If  n  is  0,
              grops  employs  no  workarounds, which is the default; it can be
              changed by modifying the broken directive in grops’s DESC file.

              Add 1 to suppress generation of %%BeginDocumentSetup and  %%End‐
              DocumentSetup  comments;  this  is  needed for early versions of
              TranScript that get confused by anything between the %%EndProlog
              comment and the first %%Page comment.

              Add 2 to omit lines in included files beginning with  %!,  which
              confuse Sun’s pageview previewer.

              Add  4  to  omit  lines in included files beginning with %%Page,
              %%Trailer and %%EndProlog; this  is  needed  for  spoolers  that
              don’t understand %%BeginDocument and %%EndDocument comments.

              Add  8 to write %!PS-Adobe-2.0 rather than %!PS-Adobe-3.0 as the
              first line of the PostScript output; this is needed  when  using
              Sun’s Newsprint with a printer that requires page reversal.

              Add 16 to omit media size information (that is, output neither a
              %%DocumentMedia  comment  nor  the setpagedevice PostScript com‐
              mand).  This was the behavior of groff 1.18.1 and earlier; it is
              needed for  older  printers  that  don’t  understand  PostScript
              LanguageLevel  2, and is also necessary if the output is further
              processed to produce an EPS file; see  subsection  “Escapsulated
              PostScript” below.

       -c n   Output n copies of each page.

       -F dir Prepend  directory  dir/devname  to the search path for font and
              device description and PostScript prologue files;  name  is  the
              name of the device, usually ps.

       -g     Generate PostScript code to guess the page length.  The guess is
              correct only if the imageable area is vertically centered on the
              page.   This option allows you to generate documents that can be
              printed on both U.S. letter and A4 paper formats without change.

       -I dir Search the directory dir for files named  in  \X'ps:  file'  and
              \X'ps:  import' escape sequences.  -I may be specified more than
              once; each dir is searched in the given order.   To  search  the
              current  working  directory before others, add “-I .” at the de‐
              sired place; it is otherwise searched last.

       -l     Use landscape orientation rather than portrait.

       -m     Turn on manual feed for the document.

       -p fmt Set  physical  dimensions  of  output  medium,  overriding   the
              papersize,  paperlength,  and  paperwidth directives in the DESC
              file.  fmt can be any argument accepted by the papersize  direc‐
              tive; see groff_font(5).

       -P prologue
              Use  the file prologue, sought in the groff font search path, as
              the PostScript prologue, overriding  the  default  (see  section
              “Files” below) and the environment variable GROPS_PROLOGUE.

       -w n   Draw  rules  (lines) with a thickness of n thousandths of an em.
              The default thickness is 40 (0.04 em).

Usage
       The input to grops must be in the format output by troff(1),  described
       in  groff_out(5).   In  addition, the device and font description files
       for the device used must meet certain requirements.  The device resolu‐
       tion must be an integer multiple of 72 times the sizescale.  The device
       description file must contain a valid paper format; see  groff_font(5).
       Each font description file must contain a directive
              internalname psname
       which says that the PostScript name of the font is psname.

       A font description file may also contain a directive
              encoding enc‐file
       which  says  that the PostScript font should be reencoded using the en‐
       coding described in enc‐file; this file should consist of a sequence of
       lines of the form
              pschar code
       where pschar is the PostScript name of the character, and code  is  its
       position  in  the encoding expressed as a decimal integer; valid values
       are in the range 0 to 255.  Lines starting with # and blank  lines  are
       ignored.   The  code  for  each character given in the font description
       file must correspond to the code for the character in encoding file, or
       to the code in the default encoding for the font if the PostScript font
       is not to be reencoded.  This code can be used with the \N  escape  se‐
       quence  in  troff  to  select the character, even if it does not have a
       groff glyph name.  Every character in the font  description  file  must
       exist in the PostScript font, and the widths given in the font descrip‐
       tion file must match the widths used in the PostScript font.  grops as‐
       sumes  that  a  character with a groff name of space is blank (makes no
       marks on the page); it can make use of such  a  character  to  generate
       more efficient and compact PostScript output.

       grops  is  able  to  display all glyphs in a PostScript font; it is not
       limited to 256 of them.  enc‐file (or the default encoding if no encod‐
       ing file is specified) just defines the order of glyphs for  the  first
       256  characters; all other glyphs are accessed with additional encoding
       vectors which grops produces on the fly.

       grops can embed fonts in a document that are necessary  to  render  it;
       this  is  called “downloading”.  Such fonts must be in PFA format.  Use
       pfbtops(1) to convert a Type 1 font in PFB format.  Downloadable  fonts
       must be listed a download file containing lines of the form
              psname file
       where  psname  is the PostScript name of the font, and file is the name
       of the file containing it; lines beginning with # and blank  lines  are
       ignored; fields may be separated by tabs or spaces.  file is sought us‐
       ing  the  same mechanism as that for groff font description files.  The
       download file itself is also sought using  this  mechanism;  currently,
       only  the  first matching file found in the device and font description
       search path is used.

       If the file containing a downloadable font or  imported  document  con‐
       forms  to the Adobe Document Structuring Conventions, then grops inter‐
       prets any comments in the files sufficiently to  ensure  that  its  own
       output  is conforming.  It also supplies any needed font resources that
       are listed in the download file as well as any needed  file  resources.
       It  is  also  able to handle inter‐resource dependencies.  For example,
       suppose that you have a downloadable font called Garamond, and  also  a
       downloadable  font  called  Garamond‐Outline  which depends on Garamond
       (typically it would be defined to copy Garamond’s font dictionary,  and
       change  the PaintType), then it is necessary for Garamond to appear be‐
       fore Garamond‐Outline in the PostScript document.  grops  handles  this
       automatically  provided  that  the downloadable font file for Garamond‐
       Outline indicates its dependence on Garamond by means of  the  Document
       Structuring  Conventions,  for  example by beginning with the following
       lines.
              %!PS-Adobe-3.0 Resource-Font
              %%DocumentNeededResources: font Garamond
              %%EndComments
              %%IncludeResource: font Garamond
       In this case, both Garamond  and  Garamond‐Outline  would  need  to  be
       listed  in  the  download file.  A downloadable font should not include
       its own name in a %%DocumentSuppliedResources comment.

       grops does not interpret  %%DocumentFonts  comments.   The  %%Document‐
       NeededResources,     %%DocumentSuppliedResources,    %%IncludeResource,
       %%BeginResource,  and  %%EndResource  comments  (or  possibly  the  old
       %%DocumentNeededFonts, %%DocumentSuppliedFonts, %%IncludeFont, %%Begin‐
       Font, and %%EndFont comments) should be used.

       The  default stroke and fill color is black.  For colors defined in the
       “rgb” color space, setrgbcolor is used; for “cmy” and “cmyk”,  setcmyk‐
       color;   and   for  “gray”,  setgray.   setcmykcolor  is  a  PostScript
       LanguageLevel 2 command and thus not available on some older printers.

   Typefaces
       Styles called R, I, B, and BI mounted at font positions 1 to  4.   Text
       fonts are grouped into families A, BM, C, H, HN, N, P, and T, each hav‐
       ing members in each of these styles.

              AR     AvantGarde‐Book
              AI     AvantGarde‐BookOblique
              AB     AvantGarde‐Demi
              ABI    AvantGarde‐DemiOblique
              BMR    Bookman‐Light
              BMI    Bookman‐LightItalic
              BMB    Bookman‐Demi
              BMBI   Bookman‐DemiItalic
              CR     Courier
              CI     Courier‐Oblique
              CB     Courier‐Bold
              CBI    Courier‐BoldOblique
              HR     Helvetica
              HI     Helvetica‐Oblique
              HB     Helvetica‐Bold
              HBI    Helvetica‐BoldOblique
              HNR    Helvetica‐Narrow
              HNI    Helvetica‐Narrow‐Oblique
              HNB    Helvetica‐Narrow‐Bold
              HNBI   Helvetica‐Narrow‐BoldOblique
              NR     NewCenturySchlbk‐Roman
              NI     NewCenturySchlbk‐Italic
              NB     NewCenturySchlbk‐Bold
              NBI    NewCenturySchlbk‐BoldItalic
              PR     Palatino‐Roman
              PI     Palatino‐Italic
              PB     Palatino‐Bold
              PBI    Palatino‐BoldItalic
              TR     Times‐Roman
              TI     Times‐Italic
              TB     Times‐Bold
              TBI    Times‐BoldItalic

       Another text font is not a member of a family.

              ZCMI   ZapfChancery‐MediumItalic

       Special fonts include S, the PostScript Symbol font; ZD, Zapf Dingbats;
       SS  (slanted  symbol),  which contains oblique forms of lowercase Greek
       letters derived from Symbol; EURO, which offers a Euro  glyph  for  use
       with  old  devices lacking it; and ZDR, a reversed version of ZapfDing‐
       bats (with symbols flipped about the vertical axis).   Most  glyphs  in
       these  fonts are unnamed and must be accessed using \N.  The last three
       are not standard PostScript fonts, but supplied by groff and  therefore
       included in the default download file.

   Device control commands
       grops  recognizes device control commands produced by the \X escape se‐
       quence, but interprets only those that begin with a “ps:” tag.

       \X'ps: exec code'
              Execute the arbitrary PostScript commands code.  The  PostScript
              currentpoint  is  set  to the groff drawing position when the \X
              escape sequence is interpreted before executing code.  The  ori‐
              gin  is  at  the  top left corner of the page; x coordinates in‐
              crease to the right, and y coordinates down the page.  A  proce‐
              dure u is defined that converts groff basic units to the coordi‐
              nate  system  in  effect  (provided  the user doesn’t change the
              scale).  For example,
                     .nr x 1i
                     \X'ps: exec \nx u 0 rlineto stroke'
              draws a horizontal line one inch long.  code may make changes to
              the graphics state, but any changes persist only to the  end  of
              the  page.  A dictionary containing the definitions specified by
              the def and mdef commands is on top of the dictionary stack.  If
              your code adds definitions to this dictionary, you should  allo‐
              cate  space  for  them  using “\X'ps: mdef n'”.  Any definitions
              persist only until the end of the page.  If you use the  \Y  es‐
              cape  sequence with an argument that names a macro, code can ex‐
              tend over multiple lines.  For example,
                     .nr x 1i
                     .de y
                     ps: exec
                     \nx u 0 rlineto
                     stroke
                     ..
                     \Yy
              is another way to draw a horizontal line  one  inch  long.   The
              single  backslash  before “nx”—the only reason to use a register
              while defining the macro “y”—is to convert a user‐specified  di‐
              mension “1i” to groff basic units which are in turn converted to
              PostScript units with the u procedure.

              grops  wraps  user‐specified  PostScript code into a dictionary,
              nothing more.  In particular, it doesn’t start and end  the  in‐
              serted  code  with save and restore, respectively.  This must be
              supplied by the user, if necessary.

       \X'ps: file name'
              This is the same as the exec command except that the  PostScript
              code is read from file name.

       \X'ps: def code'
              Place a PostScript definition contained in code in the prologue.
              There should be at most one definition per \X command.  Long de‐
              finitions  can  be  split over several \X commands; all the code
              arguments are simply joined together separated by newlines.  The
              definitions are placed in a dictionary  which  is  automatically
              pushed on the dictionary stack when an exec command is executed.
              If  you use the \Y escape sequence with an argument that names a
              macro, code can extend over multiple lines.

       \X'ps: mdef n code'
              Like def, except that code may  contain  up  to  n  definitions.
              grops  needs  to know how many definitions code contains so that
              it can create an appropriately sized  PostScript  dictionary  to
              contain them.

       \X'ps: import file llx lly urx ury width [height]'
              Import  a PostScript graphic from file.  The arguments llx, lly,
              urx, and ury give the bounding box of the graphic in the default
              PostScript coordinate system.  They should all be integers:  llx
              and  lly are the x and y coordinates of the lower left corner of
              the graphic; urx and ury are the x and y coordinates of the  up‐
              per  right  corner of the graphic; width and height are integers
              that give the desired width and height in groff basic  units  of
              the graphic.

              The  graphic  is scaled so that it has this width and height and
              translated so that the lower left corner of the graphic  is  lo‐
              cated at the position associated with \X command.  If the height
              argument  is  omitted it is scaled uniformly in the x and y axes
              so that it has the specified width.

              The contents of the \X command are not interpreted by troff,  so
              vertical  space  for the graphic is not automatically added, and
              the width and height arguments are not allowed to have  attached
              scaling indicators.

              If  the  PostScript file complies with the Adobe Document Struc‐
              turing Conventions and contains a  %%BoundingBox  comment,  then
              the  bounding  box  can  be  automatically extracted from within
              groff input by using the psbb request.

              See groff_tmac(5) for a description of  the  PSPIC  macro  which
              provides  a  convenient  high‐level  interface  for inclusion of
              PostScript graphics.

       \X'ps: invis'
       \X'ps: endinvis'
              No output is generated for text and drawing  commands  that  are
              bracketed  with  these \X commands.  These commands are intended
              for use  when  output  from  troff  is  previewed  before  being
              processed with grops; if the previewer is unable to display cer‐
              tain characters or other constructs, then other substitute char‐
              acters  or  constructs  can be used for previewing by bracketing
              them with these \X commands.

              For example, gxditview is not able to  display  a  proper  \[em]
              character because the standard X11 fonts do not provide it; this
              problem can be overcome by executing the following request

                     .char \[em] \X'ps: invis'\
                     \Z'\v'‐.25m'\h'.05m'\D'l .9m 0'\h'.05m''\
                     \X'ps: endinvis'\[em]

              In this case, gxditview is unable to display the \[em] character
              and draws the line, whereas grops prints the \[em] character and
              ignores  the  line (this code is already in file Xps.tmac, which
              is loaded if a document intended for  grops  is  previewed  with
              gxditview).

       If  a  PostScript  procedure BPhook has been defined via a “ps: def” or
       “ps: mdef” device control command, it is executed at the  beginning  of
       every  page  (before anything is drawn or written by groff).  For exam‐
       ple, to underlay the page contents with the word “DRAFT” in light gray,
       you might use

              .de XX
              ps: def
              /BPhook
              { gsave .9 setgray clippath pathbbox exch 2 copy
                .5 mul exch .5 mul translate atan rotate pop pop
                /NewCenturySchlbk‐Roman findfont 200 scalefont setfont
                (DRAFT) dup stringwidth pop -.5 mul -70 moveto show
                grestore }
              def
              ..
              .devicem XX

       Or, to cause lines and polygons to be drawn with  square  linecaps  and
       mitered  linejoins instead of the round linecaps and linejoins normally
       used by grops, use
              .de XX
              ps: def
              /BPhook { 2 setlinecap 0 setlinejoin } def
              ..
              .devicem XX
       (square linecaps, as opposed to butt linecaps  (“0  setlinecap”),  give
       true  corners  in  boxed  tables even though the lines are drawn uncon‐
       nected).

   Encapsulated PostScript
       grops itself doesn’t emit  bounding  box  information.   The  following
       script, groff2eps, produces an EPS file.

              #! /bin/sh
              groff -P-b16 "$1" > "$1".ps
              gs -dNOPAUSE -sDEVICE=bbox -- "$1".ps 2> "$1".bbox
              sed -e "/^%%Orientation/r $1.bbox" \
                  -e "/^%!PS-Adobe-3.0/s/$/ EPSF-3.0/" "$1".ps > "$1".eps
              rm "$1".ps "$1".bbox

       You can then use “groff2eps foo” to convert file foo to foo.eps.

   TrueType and other font formats
       TrueType  fonts  can  be  used with grops if converted first to Type 42
       format, a PostScript wrapper equivalent to the PFA format described  in
       pfbtops(1).   Several methods exist to generate a Type 42 wrapper; some
       of them involve the use of a  PostScript  interpreter  such  as  Ghost‐
       script—see gs(1).

       One  approach is to use FontForge ⟨https://fontforge.org/⟩, a font edi‐
       tor that can convert most outline font formats.  Here’s an  example  of
       using  the  Roboto  Slab  Serif font with groff.  Several variables are
       used so that you can more easily adapt it into your own script.

           MAP=/usr/share/groff/1.23.0/font/devps/generate/text.map
           TTF=/usr/share/fonts/truetype/roboto/slab/RobotoSlab-Regular.ttf
           BASE=$(basename "$TTF")
           INT=${BASE%.ttf}
           PFA=$INT.pfa
           AFM=$INT.afm
           GFN=RSR
           DIR=$HOME/.local/groff/font
           mkdir -p "$DIR"/devps
           fontforge -lang=ff -c "Open(\"$TTF\");\
           Generate(\"$DIR/devps/$PFA\");"
           afmtodit "$DIR/devps/$AFM" "$MAP" "$DIR/devps/$GFN"
           printf "$BASE\t$PFA\n" >> "$DIR/devps/download"

       fontforge and afmtodit may generate warnings depending on  the  attrib‐
       utes of the font.  The test procedure is simple.

           printf ".ft RSR\nHello, world!\n" | groff -F "$DIR" > hello.ps

       Once you’re satisfied that the font works, you may want to generate any
       available  related  styles  (for instance, Roboto Slab also has “Bold”,
       “Light”, and “Thin” styles) and set up GROFF_FONT_PATH in your environ‐
       ment to include the directory you keep the generated fonts in  so  that
       you don’t have to use the -F option.

Font installation
       The following is a step‐by‐step font installation guide for grops.

       • Convert  your  font  to something groff understands.  This is a Post‐
         Script Type 1 font in PFA format or a PostScript Type  42  font,  to‐
         gether with an AFM file.  A PFA file begins as follows.
                %!PS-AdobeFont-1.0:
         A  PFB file contains this string as well, preceded by some non‐print‐
         ing bytes.  If your font is in PFB  format,  use  groff’s  pfbtops(1)
         program  to  convert it to PFA.  For TrueType and other font formats,
         we recommend fontforge, which can convert most outline font  formats.
         A Type 42 font file begins as follows.
                %!PS-TrueTypeFont
         This is a wrapper format for TrueType fonts.  Old PostScript printers
         might not support them (that is, they might not have a built‐in True‐
         Type font interpreter).  In the following steps, we will consider the
         use   of  CTAN’s  BrushScriptX‐Italic  ⟨https://ctan.org/tex-archive/
         fonts/brushscr⟩ font in PFA format.

       • Convert the AFM file to  a  groff  font  description  file  with  the
         afmtodit(1) program.  For instance,
                $ afmtodit BrushScriptX-Italic.afm text.map BSI
         converts  the  Adobe  Font Metric file BrushScriptX-Italic.afm to the
         groff font description file BSI.

         If you have a font family which  provides  regular  upright  (roman),
         bold, italic, and bold‐italic styles (where “italic” may be “oblique”
         or  “slanted”),  we  recommend using the letters R, B, I, and BI, re‐
         spectively, as suffixes to the  groff  font  family  name  to  enable
         groff’s  font  family  and  style  selection features.  An example is
         groff’s built‐in support for Times: the font family name is  abbrevi‐
         ated  as  T,  and  the groff font names are therefore TR, TB, TI, and
         TBI.  In our example, however, the BrushScriptX font is available  in
         a single style only, italic.

       • Install the groff font description file(s) in a devps subdirectory in
         the  search  path  that  groff uses for device and font file descrip‐
         tions.  See the GROFF_FONT_PATH entry  in  section  “Environment”  of
         troff(1)  for the current value of the font search path.  While groff
         doesn’t directly use AFM files, it is  a  good  idea  to  store  them
         alongside its font description files.

       • Register  fonts in the devps/download file so they can be located for
         embedding in PostScript files grops generates.  Only the first  down‐
         load  file encountered in the font search path is read.  If in doubt,
         copy the default download file (see section  “Files”  below)  to  the
         first  directory  in  the  font search path and add your fonts there.
         The PostScript font name used by grops is stored in the  internalname
         field in the groff font description file.  (This name does not neces‐
         sarily  resemble the font’s file name.)  We add the following line to
         download.
                BrushScriptX-Italic→BrushScriptX-Italic.pfa
         A tab character, depicted as →, separates the fields.

       • Test the selection and embedding of the new font.
                printf "\\f[BSI]Hello, world!\n" | groff -T ps -P -e >hello.ps
                see hello.pdf

Old fonts
       groff versions 1.19.2 and earlier contained descriptions of a  slightly
       different set of the base 35 PostScript level 2 fonts defined by Adobe.
       The  older  set  has  229 glyphs and a larger set of kerning pairs; the
       newer one has 314 glyphs and includes the Euro  glyph.   For  backwards
       compatibility,  these  old  font descriptions are also installed in the
       /usr/share/groff/1.23.0/oldfont/devps directory.

       To use them, make sure that grops finds the fonts  before  the  default
       system  fonts  (with the same names): either give grops the -F command‐
       line option,
              $ groff -Tps -P-F -P/usr/share/groff/1.23.0/oldfont ...
       or add the directory to groff’s font and device description search path
       environment variable,
              $ GROFF_FONT_PATH=/usr/share/groff/1.23.0/oldfont \
                     groff -Tps ...
       when the command runs.

Environment
       GROFF_FONT_PATH
              A list of directories in which to seek the selected  output  de‐
              vice’s  directory  of  device  and  font description files.  See
              troff(1) and groff_font(5).

       GROPS_PROLOGUE
              If this is set to foo, then grops uses the file foo (in the font
              path) instead of the default prologue file prologue.  The option
              -P overrides this environment variable.

       SOURCE_DATE_EPOCH
              A timestamp (expressed as seconds since the Unix epoch)  to  use
              as  the  output creation timestamp in place of the current time.
              The time is converted to human‐readable form using ctime(3)  and
              recorded in a PostScript comment.

       TZ     The  time zone to use when converting the current time (or value
              of SOURCE_DATE_EPOCH) to human‐readable form; see tzset(3).

Files
       /usr/share/groff/1.23.0/font/devps/DESC
              describes the ps output device.

       /usr/share/groff/1.23.0/font/devps/F
              describes the font known as F on device ps.

       /usr/share/groff/1.23.0/font/devps/download
              lists fonts available for embedding within the PostScript  docu‐
              ment (or download to the device).

       /usr/share/groff/1.23.0/font/devps/prologue
              is  the  default  PostScript  prologue  prefixed to every output
              file.

       /usr/share/groff/1.23.0/font/devps/text.enc
              describes the encoding scheme used by  most  PostScript  Type  1
              fonts;  the encoding directive of font description files for the
              ps device refers to it.

       /usr/share/groff/1.23.0/tmac/ps.tmac
              defines macros for use with the ps output device.  It  is  auto‐
              matically  loaded  by  troffrc  when the ps output device is se‐
              lected.

       /usr/share/groff/1.23.0/tmac/pspic.tmac
              defines the PSPIC macro for embedding images in a document;  see
              groff_tmac(5).  It is automatically loaded by troffrc.

       /usr/share/groff/1.23.0/tmac/psold.tmac
              provides  replacement  glyphs  for text fonts that lack complete
              coverage of the ISO Latin‐1 character set; using it,  groff  can
              produce  glyphs like eth (ð) and thorn (þ) that older PostScript
              printers do not natively support.

       grops creates temporary files using  the  template  “gropsXXXXXX”;  see
       groff(1) for details on their storage location.

See also
       PostScript  Language  Document  Structuring  Conventions  Specification
       ⟨http://partners.adobe.com/public/developer/en/ps/5001.DSC_Spec.pdf⟩

       afmtodit(1),    groff(1),    troff(1),    pfbtops(1),    groff_char(7),
       groff_font(5), groff_out(5), groff_tmac(5)

groff 1.23.0                      2 July 2023                         grops(1)
───────────────────────────────────────────────────────────────────────────────
grotty(1)                   General Commands Manual                  grotty(1)

Name
       grotty - groff output driver for typewriter‐like (terminal) devices

Synopsis
       grotty [-dfho] [-i|-r] [-F dir] [file ...]

       grotty -c [-bBdfhouU] [-F dir] [file ...]

       grotty --help

       grotty -v
       grotty --version

Description
       The  GNU  roff  TTY (“Teletype”) output driver translates the output of
       troff(1) into a form suitable for  typewriter‐like  devices,  including
       terminal  emulators.   Normally, grotty is invoked by groff(1) when the
       latter is given one of  the  “-T  ascii”,  “-T  latin1”,  -Tlatin1,  or
       “-T utf8” options on systems using ISO character encoding standards, or
       with  “-T cp1047” or “-T utf8” on EBCDIC‐based hosts.  (In this instal‐
       lation, ps is the default output device.)  Use  groff’s  -P  option  to
       pass  any  options  shown  above  to  grotty.  If no file arguments are
       given, or if file is “-”, grotty reads the standard input stream.  Out‐
       put is written to the standard output stream.

       By default, grotty emits SGR escape sequences (from ISO 6429, popularly
       called “ANSI escapes”) to change text attributes (bold, italic,  under‐
       line, reverse video [“negative image”] and colors).  Devices supporting
       the appropriate sequences can view roff documents using eight different
       background  and  foreground  colors.  Following ISO 6429, the following
       colors are defined in tty.tmac: black, white, red, green, blue, yellow,
       magenta, and cyan.  Unrecognized  colors  are  mapped  to  the  default
       color,  which  is dependent on the settings of the terminal.  OSC 8 hy‐
       perlinks are produced for these devices.

       In keeping with long‐standing practice and the rarity of terminals (and
       emulators) that support oblique or italic  fonts,  italicized  text  is
       represented with underlining by default—but see the -i option below.

   SGR and OSC support in pagers
       When  paging  grotty’s  output with less(1), the latter program must be
       instructed to pass SGR and OSC sequences through to the device; its  -R
       option  is  one  way  to achieve this (less version 566 or later is re‐
       quired for OSC 8 support).  Consequently,  programs  like  man(1)  that
       page roff documents with less must call it with an appropriate option.

   Legacy output format
       The  -c option tells grotty to use an output format compatible with pa‐
       per terminals, like the Teletype machines for which roff and nroff were
       first developed but which are no longer in wide use.   SGR  escape  se‐
       quences  are  not  emitted; bold, italic, and underlining character at‐
       tributes are thus not manipulated.  Instead, grotty overstrikes, repre‐
       senting a bold character c with the sequence “c BACKSPACE c”, an italic
       character c with the sequence “_ BACKSPACE c”, and  bold  italics  with
       “_  BACKSPACE  c  BACKSPACE c”.  This rendering is inherently ambiguous
       when the character c is itself the underscore.

       The legacy output format can be rendered on a video terminal (or emula‐
       tor) by piping grotty’s output through ul(1),  which  may  render  bold
       italics  as  reverse  video.   Some implementations of more(1) are also
       able to display these sequences; you may wish to experiment  with  that
       command’s  -b option.  less renders legacy bold and italics without re‐
       quiring options.  In contrast to the terminal output  drivers  of  some
       other  roff  implementations,  grotty never outputs reverse line feeds.
       There is therefore no need to filter its output through col(1).

   Device control commands
       grotty understands one device control function produced by the roff  \X
       escape sequence in a document.

       \X'tty: link [uri [key=value] ...]'
              Embed  a  hyperlink  using  the  OSC 8 terminal escape sequence.
              Specifying uri starts hyperlinked text, and omitting it ends the
              hyperlink.  When  uri  is  present,  any  number  of  additional
              key/value  pairs  can  be specified; their interpretation is the
              responsibility of the pager or terminal.  Spaces or tabs  cannot
              appear literally in uri, key, or value; they must be represented
              in an alternate form.

   Device description files
       If  the DESC file for the character encoding contains the “unicode” di‐
       rective, grotty emits Unicode characters in UTF‐8 encoding.  Otherwise,
       it emits characters in a single‐byte encoding depending on the data  in
       the font description files.  See groff_font(5).

       A  font description file may contain a directive “internalname n” where
       n is a decimal integer.  If the 01 bit in n is set, then  the  font  is
       treated  as an italic font; if the 02 bit is set, then it is treated as
       a bold font.

   Typefaces
       grotty supports the standard four styles:  R  (roman),  I  (italic),  B
       (bold),  and  BI  (bold‐italic).  Because the output driver operates in
       nroff mode, attempts to set or change the font family or type size  are
       ignored.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -b     Suppress the use of overstriking for bold characters  in  legacy
              output format.

       -B     Use  only overstriking for bold‐italic characters in legacy out‐
              put format.

       -c     Use grotty’s legacy output format (see subsection “Legacy output
              format” above).  SGR and OSC escape sequences are not emitted.

       -d     Ignore all \D drawing escape sequences in  the  input.   By  de‐
              fault,  grotty  renders  \D'l...'  escape sequences that have at
              least one zero argument (and so are either horizontal or  verti‐
              cal)  using Unicode box drawing characters (for the utf8 device)
              or the -, |, and + characters (for all other  devices).   grotty
              handles \D'p...' escape sequences that consist entirely of hori‐
              zontal and vertical lines similarly.

       -f     Emit a form feed at the end of each page having no output on its
              last line.

       -F dir Prepend  directory  dir/devname  to the search path for font and
              device description files; name  describes  the  output  device’s
              character encoding, one of ascii, latin1, utf8, or cp1047.

       -h     Use  literal  horizontal tab characters in the output.  Tabs are
              assumed to be set every 8 columns.

       -i     Render oblique‐styled fonts (I and BI) with  the  SGR  attribute
              for  italic  text  rather  than underlined text.  Many terminals
              don’t  support  this   attribute;   however,   xterm(1),   since
              patch #314 (2014‐12‐28), does.  Ignored if -c is also specified.

       -o     Suppress  overstriking  (other  than  for bold and/or underlined
              characters when the legacy output format is in use).

       -r     Render oblique‐styled fonts (I and BI) with  the  SGR  attribute
              for  reverse video text rather than underlined text.  Ignored if
              -c or -i is also specified.

       -u     Suppress the use of underlining for italic characters in  legacy
              output format.

       -U     Use only underlining for bold‐italic characters in legacy output
              format.

Environment
       GROFF_FONT_PATH
              A  list  of directories in which to seek the selected output de‐
              vice’s directory of device  and  font  description  files.   See
              troff(1) and groff_font(5).

       GROFF_NO_SGR
              If  set, grotty’s legacy output format is used just as if the -c
              option were specified; see  subsection  “Legacy  output  format”
              above.

Files
       /usr/share/groff/1.23.0/font/devascii/DESC
              describes the ascii output device.

       /usr/share/groff/1.23.0/font/devascii/F
              describes the font known as F on device ascii.

       /usr/share/groff/1.23.0/font/devcp1047/DESC
              describes the cp1047 output device.

       /usr/share/groff/1.23.0/font/devcp1047/F
              describes the font known as F on device cp1047.

       /usr/share/groff/1.23.0/font/devlatin1/DESC
              describes the latin1 output device.

       /usr/share/groff/1.23.0/font/devlatin1/F
              describes the font known as F on device latin1.

       /usr/share/groff/1.23.0/font/devutf8/DESC
              describes the utf8 output device.

       /usr/share/groff/1.23.0/font/devutf8/F
              describes the font known as F on device utf8.

       /usr/share/groff/1.23.0/tmac/tty.tmac
              defines  macros for use with the ascii, cp1047, latin1, and utf8
              output devices.  It is automatically loaded by troffrc when  any
              of those output devices is selected.

       /usr/share/groff/1.23.0/tmac/tty-char.tmac
              defines fallback characters for use with grotty.  See nroff(1).

Limitations
       grotty is intended only for simple documents.

       • There is no support for fractional horizontal or vertical motions.

       • roff \D escape sequences producing anything other than horizontal and
         vertical lines are not supported.

       • Characters above the first line (that is, with a vertical drawing po‐
         sition of 0) cannot be rendered.

       • Color handling differs from other output drivers.  The groff requests
         and  escape sequences that set the stroke and fill colors instead set
         the foreground and background character cell colors, respectively.

Examples
       The following groff document exercises several features for which  out‐
       put  device  support  varies:  (1)  bold  style; (2) italic (underline)
       style; (3) bold‐italic style; (4) character composition by overstriking
       (“coöperate”); (5) foreground color; (6) background color; and (7) hor‐
       izontal and vertical line‐drawing.

              You might see \f[B]bold\f[] and \f[I]italic\f[].
              Some people see \f[BI]both\f[].
              If the output device does (not) co\z\[ad]operate,
              you might see \m[red]red\m[].
              Black on cyan can have a \M[cyan]\m[black]prominent\m[]\M[]
              \D'l 1i 0'\D'l 0 2i'\D'l 1i 0' look.
              .\" If in nroff mode, end page now.
              .if n .pl \n[nl]u

       Given the foregoing input, compare and contrast the output of the  fol‐
       lowing.

              $ groff -T ascii file
              $ groff -T utf8 -P -i file
              $ groff -T utf8 -P -c file | ul

See also
       “Control  Functions  for  Coded  Character Sets” (ECMA‐48) 5th edition,
       Ecma International, June 1991.  A gratis version of ISO 6429, this doc‐
       ument includes a normative description of SGR escape sequences.  Avail‐
       able at  ⟨http://www.ecma-international.org/publications/files/ECMA-ST/
       Ecma-048.pdf⟩.

       “Hyperlinks  in Terminal Emulators” ⟨https://gist.github.com/egmontkob/
       eb114294efbcd5adb1944c9f3cb5feda⟩, Egmont Koblinger.

       groff(1), troff(1), groff_out(5), groff_font(5), groff_char(7),  ul(1),
       more(1), less(1), man(1)

groff 1.23.0                      2 July 2023                        grotty(1)
───────────────────────────────────────────────────────────────────────────────
gxditview(1)                General Commands Manual               gxditview(1)

Name
       gxditview - display groff intermediate output files in X11

Synopsis
       gxditview [X‐toolkit‐option ...] [-backingStore backing‐store‐type]
                 [-filename file] [-page page‐number] [-printCommand command]
                 [-resolution resolution] file

       gxditview -help
       gxditview --help

       gxditview -version
       gxditview --version

Description
       gxditview  interprets  and  displays  the intermediate output format of
       groff(1) on an X11 display.  It uses the standard X11 fonts, so it does
       not require access to the server machine for font loading.   There  are
       several ways to use gxditview.

       The intermediate output format of groff, documented in groff_out(5), is
       produced  by  troff or the -Z option to groff.  It can be viewed by ex‐
       plicitly calling  “gxditview  file”.   If  the  file  operand  is  “-”,
       gxditview  will read the standard input stream; file cannot be omitted.
       The intermediate output format of groff is device‐independent  but  not
       device‐agnostic.  gxditview can view it for all typesetter devices, but
       the quality is device‐dependent.  gxditview will not display output for
       terminal (nroff) devices.

       The  best  results  are achieved with the X* devices for groff’s -T op‐
       tion, of which there are four: -TX75, -TX75-12, -TX100, and  -TX100-12.
       They  differ by the X resolution (75 or 100 dots per inch) and the base
       point size (10 or 12 points).  They are especially built for gxditview.
       When using one of these, groff generates the  intermediate  output  for
       this device and calls gxditview automatically for viewing.

       -X  produces  good results only with -Tps, -TX75, -TX75-12, -TX100, and
       -TX100-12.  The default resolution for previewing -Tps output is 75dpi;
       this can be changed with the -resolution option.

       While gxditview is running, the left mouse button brings up a menu with
       several entries.

       Next Page    Display the next page.

       Previous Page
                    Display the previous page.

       Select Page  Select a particular numbered page specified  by  a  dialog
                    box.

       Print        Print the groff intermediate output using a command speci‐
                    fied  by a dialog box.  The default command initially dis‐
                    played is controlled by the printCommand  application  re‐
                    source, and by the -printCommand option.

       Open         Open  for  display  a  new file specified by a dialog box.
                    The file should contain groff intermediate output.  If the
                    filename starts with a bar or pipe symbol, “|” it will  be
                    interpreted as a command from which to read.

       Quit         Exit from gxditview.

       The  menu  entries correspond to actions with similar but not identical
       names, which can also be accessed with keyboard accelerators.   The  n,
       Space,  Return,  and Next (PgDn) keys are bound to the NextPage action.
       The p, b, BackSpace, Delete, and Prior (PgUp) keys  are  bound  to  the
       PreviousPage action.  The g key is bound to the SelectPage action.  The
       o  key is bound to the OpenFile action.  The q key is bound to the Quit
       action.  The r key is bound to a Rerasterize action which  rereads  the
       current file, and redisplays the current page; if the current file is a
       command,  the  command  will be re‐executed.  Vertical scrolling can be
       done with the k and j keys; horizontal scrolling is bound to the h  and
       l  keys.   The arrow keys (up, down, left, and right) are also bound to
       the obvious scrolling actions.

       The paperlength and paperwidth commands in the DESC file  describing  a
       groff  output  device  specify the length and width in machine units of
       the virtual page displayed by gxditview; see groff_font(5).

   X defaults
       This program uses the Dvi widget from the X  Toolkit.   It  understands
       all of the core resource names and classes as well as:

       width (class Width)
              Specifies the width of the window.

       height (class Height)
              Specifies the height of the window.

       foreground (class Foreground)
              Specifies the default foreground color.

       font (class Font)
              Specifies the font to be used for error messages.

       fontMap (class FontMap)
              Specifies  the  mapping  from  groff font names to X font names.
              This must be a string containing a sequence of lines.  Each line
              contains two whitespace‐separated fields: firstly the groff font
              name, and secondly the XLFD (X Logical Font  Description).   The
              default is shown in subsection “Default font map” below.

   Default font map
       XLFDs  are  long  and  unwieldy, so some lines are shown broken and in‐
       dented below.

       TR  -adobe-times-medium-r-normal--*-100-*-*-*-*-iso8859-1\n\
       TI  -adobe-times-medium-i-normal--*-100-*-*-*-*-iso8859-1\n\
       TB  -adobe-times-bold-r-normal--*-100-*-*-*-*-iso8859-1\n\
       TBI -adobe-times-bold-i-normal--*-100-*-*-*-*-iso8859-1\n\
       CR  -adobe-courier-medium-r-normal--*-100
               -*-*-*-*-iso8859-1\n\
       CI  -adobe-courier-medium-o-normal
               --*-100-*-*-*-*-iso8859-1\n\
       CB  -adobe-courier-bold-r-normal--*-100-*-*-*-*-iso8859-1\n\
       CBI -adobe-courier-bold-o-normal--*-100-*-*-*-*-iso8859-1\n\
       HR  -adobe-helvetica-medium-r-normal
               --*-100-*-*-*-*-iso8859-1\n\
       HI  -adobe-helvetica-medium-o-normal
               --*-100-*-*-*-*-iso8859-1\n\
       HB  -adobe-helvetica-bold-r-normal
               --*-100-*-*-*-*-iso8859-1\n\
       HBI -adobe-helvetica-bold-o-normal
               --*-100-*-*-*-*-iso8859-1\n\
       NR  -adobe-new century schoolbook-medium-r-normal--*-100
               -*-*-*-*-iso8859-1\n\
       NI  -adobe-new century schoolbook-medium-i-normal--*-100
               -*-*-*-*-iso8859-1\n\
       NB  -adobe-new century schoolbook-bold-r-normal--*-100
               -*-*-*-*-iso8859-1\n\
       NBI -adobe-new century schoolbook-bold-i-normal--*-100
               -*-*-*-*-iso8859-1\n\
       S   -adobe-symbol-medium-r-normal--*-100
               -*-*-*-*-adobe-fontspecific\n\
       SS  -adobe-symbol-medium-r-normal--*-100
               -*-*-*-*-adobe-fontspecific\n\

Options
       -help and --help display a usage message, while -version and  --version
       show version information; all exit afterward.

       gxditview  accepts  all  of the standard X Toolkit command‐line options
       along with the additional options listed below.

       -page  This option specifies the page number of the document to be dis‐
              played.

       -backingStore backing‐store‐type
              Because redisplay of the groff intermediate  output  window  can
              take  a  perceiptible  amount  of  time,  this option causes the
              server to save the window contents so that when it  is  scrolled
              around  the  viewport, the window is painted from contents saved
              in backing store.  backing‐store‐type  can  be  one  of  Always,
              WhenMapped or NotUseful.

       -printCommand command
              The  default  command  displayed in the dialog box for the Print
              menu entry will be command.

       -resolution res
              The groff intermediate output file will be displayed at a  reso‐
              lution  of  res dots per inch, unless the DESC file contains the
              X11 command, in which case the device resolution will  be  used.
              This  corresponds  to the Dvi widget’s resolution resource.  The
              default is 75.

       -filename string
              The default filename displayed in the dialog box  for  the  Open
              menu  entry will be string.  This can be either a filename, or a
              command starting with “|”.

       The following standard X Toolkit command‐line  arguments  are  commonly
       used with gxditview.

       -bg color
              This option specifies the color to use for the background of the
              window.  The default is “white”.

       -bd color
              This  option  specifies  the  color to use for the border of the
              window.  The default is “black”.

       -bw number
              This option specifies the width in pixels  of  the  border  sur‐
              rounding the window.

       -fg color
              This option specifies the color to use for displaying text.  The
              default is “black”.

       -fn font
              This  option specifies the font to be used for displaying widget
              text.  The default is “fixed”.

       -rv    This option indicates that reverse video should be simulated  by
              swapping the foreground and background colors.

       -geometry geometry
              This  option  specifies  the  preferred size and position of the
              window.

       -display host:display
              This option specifies the X server to contact.

       -xrm resourcestring
              This option specifies a resource string to be used.

Environment
       GROFF_FONT_PATH
              A list of directories in which to seek the selected  output  de‐
              vice’s  directory  of  device  and  font description files.  See
              troff(1) and groff_font(5).

Files
       /etc/X11/app-defaults/GXditview
       /etc/X11/app-defaults/GXditview-color
              define X application defaults for gxditview.  Users can override
              these values in the .Xdefaults file,  normally  located  in  the
              user’s home directory.  See appres(1) and xrdb(1).

       /usr/share/groff/1.23.0/font/devX100/DESC
              describes the X100 output device.

       /usr/share/groff/1.23.0/font/devX100/F
              describes the font known as F on device X100.

       /usr/share/groff/1.23.0/font/devX100-12/DESC
              describes the X100-12 output device.

       /usr/share/groff/1.23.0/font/devX100-12/F
              describes the font known as F on device X100-12.

       /usr/share/groff/1.23.0/font/devX75/DESC
              describes the X75 output device.

       /usr/share/groff/1.23.0/font/devX75/F
              describes the font known as F on device X75.

       /usr/share/groff/1.23.0/font/devX75-12/DESC
              describes the X75-12 output device.

       /usr/share/groff/1.23.0/font/devX75-12/F
              describes the font known as F on device X75-12.

       /usr/share/groff/1.23.0/tmac/X.tmac
              defines  macros  for use with the X100, X100-12, X75, and X75-12
              output devices.  It is automatically loaded by troffrc when  any
              of those output devices is selected.

       /usr/share/groff/1.23.0/tmac/Xps.tmac
              sets  up  troff to use gxditview as a previewer for device‐inde‐
              pendent output targeting the ps output device.  It is  automati‐
              cally  loaded  by troffrc when troff is given the options -X and
              -Tps.

Examples
       The following command views this man page with a base point size of 12.

              groff -TX100-12 -man gxditview.1

       The quality of the result depends mainly on the chosen point  size  and
       display resolution; for rapid previewing, however, something like
              groff -X -P-resolution -P100 document
       yields acceptable results.

Authors
       gxditview  and  its  predecessor xditview were written by Keith Packard
       (MIT X Consortium), Richard L. Hyde (Purdue), David Slattengren (Berke‐
       ley), Malcolm Slaney (Schlumberger Palo  Alto  Research),  Mark  Moraes
       (University of Toronto), and James Clark.

       This  program is derived from xditview; portions of xditview originated
       in xtroff, which was derived from suntroff.

See also
       “X Logical Font Description  Conventions”  ⟨https://www.x.org/releases/
       X11R7.6/doc/xorg-docs/specs/XLFD/xlfd.html⟩, by Jim Flowers and Stephen
       Gildea.

       X(7), xrdb(1), xditview(1), groff(1), groff_out(5)

groff 1.23.0                      2 July 2023                     gxditview(1)
───────────────────────────────────────────────────────────────────────────────
hpftodit(1)                 General Commands Manual                hpftodit(1)

Name
       hpftodit - create font description files for use with groff and grolj4

Synopsis
       hpftodit [-aqs] [-i n] tfm‐file map‐file font‐description

       hpftodit -d tfm‐file [map‐file]

       hpftodit --help

       hpftodit -v
       hpftodit --version

Description
       hpftodit creates a font description file for use with a Hewlett‐Packard
       LaserJet  4‐series  (or newer) printer with the grolj4(1) output driver
       of groff(1), using data from an HP tagged font metric (TFM) file.  tfm‐
       file is the name of the font’s TFM file; Intellifont and  TrueType  TFM
       files  are  supported, but symbol set TFM files are not.  map‐file is a
       file giving the groff special character identifiers for glyphs  in  the
       font; this file should consist of a sequence of lines of the form
              m u c1 c2 ... [# comment]
       where  m  is  a  decimal  integer giving the glyph’s MSL (Master Symbol
       List) number, u is a hexadecimal integer giving its  Unicode  character
       code, and c1, c2, ...  are its groff glyph names (see groff_char(7) for
       a  list).   The  values can be separated by any number of spaces and/or
       tabs.  The Unicode value must use uppercase hexadecimal digits A–F, and
       must lack a leading “0x”, “u”, or “U+”.  Unicode  values  corresponding
       to   composite   glyphs   are   decomposed;  that  is  “u00C0”  becomes
       “u0041_0300”.  A glyph without a groff special character identifier may
       be named uXXXX if the glyph corresponds to a Unicode value,  or  as  an
       unnamed  glyph “---”.  If the given Unicode value is in the Private Use
       Area (PUA) (0xE000–0xF8FF), the glyph is included as an unnamed  glyph.
       Refer  to groff_diff(1) for additional information about unnamed glyphs
       and how to access them.

       Blank lines and lines beginning with “#” are ignored.  A “#”  following
       one or more groff names begins a comment.  Because “#” is a valid groff
       name, it must appear first in a list of groff names if a comment is in‐
       cluded, as in
              3   0023   #   # number sign
       or
              3   0023   # sh   # number sign
       whereas in
              3   0023   sh #   # number sign
       the first “#” is interpreted as the beginning of the comment.

       Output  is  written in groff_font(5) format to font‐description, a file
       named for the intended groff font name; if this  operand  is  “-”,  the
       font description is written to the standard output stream.

       If  the  -i  option  is  used,  hpftodit automatically will generate an
       italic correction, a left italic correction, and a subscript correction
       for each glyph (the significance of these parameters  is  explained  in
       groff_font(5)).

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -a     Include glyphs in the TFM file that are  not  included  in  map‐
              file.   A  glyph  with  corresponding Unicode value is given the
              name uXXXX; a glyph without a Unicode value is  included  as  an
              unnamed  glyph  “---”.  A glyph with a Unicode value in the Pri‐
              vate Use Area (0xE000–0xF8FF) is also  included  as  an  unnamed
              glyph.

              This  option provides a simple means of adding Unicode‐named and
              unnamed glyphs to a font without including them in the map file,
              but it affords little control over which glyphs are placed in  a
              regular  font and which are placed in a special font.  The pres‐
              ence or absence of the -s option has some effect on which glyphs
              are included: without  it,  only  the  “text”  symbol  sets  are
              searched  for  matching glyphs; with it, only the “mathematical”
              symbol sets are searched.  Nonetheless, restricting  the  symbol
              sets  searched  isn’t  very  selective—many glyphs are placed in
              both regular and special fonts.  Normally,  -a  should  be  used
              only as a last resort.

       -d     Dump  information  about  the  TFM  file  to the standard output
              stream; use this to ensure that a TFM file is a proper match for
              a font, and that its contents are suitable.  The information in‐
              cludes the values of important TFM tags and a  listing  (by  MSL
              number  for  Intellifont TFM files or by Unicode value for True‐
              Type TFM files) of the glyphs included in  the  TFM  file.   The
              unit of measure “DU” for some tags indicates design units; there
              are 8782 design units per em for Intellifont fonts, and 2048 de‐
              sign units per em for TrueType fonts.  Note that the accessibil‐
              ity  of  a  glyph depends on its inclusion in a symbol set; some
              TFM files list many glyphs but only a few symbol sets.

              The glyph listing includes the glyph index within the TFM  file,
              the  MSL or Unicode value, and the symbol set and character code
              that will be used to print the glyph.   If  map‐file  is  given,
              groff  names  are  given for matching glyphs.  If only the glyph
              index and MSL or Unicode value are given, the glyph does not ap‐
              pear in any supported symbol set and cannot be printed.

              With the -d option, map‐file is optional, and output‐font is ig‐
              nored if given.

       -i n   Generate an italic correction for each glyph so that  its  width
              plus  its  italic  correction is equal to n thousandths of an em
              plus the amount by which the right edge of the glyphs’s bounding
              box is to the right of its origin.  If a negative italic correc‐
              tion would result, use a zero italic correction instead.

              Also generate a subscript correction equal to the product of the
              tangent of the slant of the font and four fifths of the x‐height
              of the font.  If a subscript correction greater than the  italic
              correction would result, use a subscript correction equal to the
              italic correction instead.

              Also generate a left italic correction for each glyph equal to n
              thousandths  of  an em plus the amount by which the left edge of
              the glyphs’s bounding box is to the left  of  its  origin.   The
              left italic correction may be negative.

              This  option  normally  is  needed  only  with italic or oblique
              fonts; a value of 50 (0.05 em) usually is a reasonable choice.

       -q     Suppress warnings about glyphs in the map  file  that  were  not
              found  in  the  TFM  file.  Warnings never are given for unnamed
              glyphs or by glyphs named by their Unicode values.  This  option
              is  useful  when  sending the output of hpftodit to the standard
              output stream.

       -s     Add the special directive to the font description file,  affect‐
              ing  the  order  in  which  HP symbol sets are searched for each
              glyph.  Without this option, the “text” sets are searched before
              the “mathematical” symbol sets.  With it, the  search  order  is
              reversed.

Files
       /usr/share/groff/1.23.0/font/devlj4/DESC
              describes the lj4 output device.

       /usr/share/groff/1.23.0/font/devlj4/F
              describes the font known as F on device lj4.

       /usr/share/groff/1.23.0/font/devlj4/generate/Makefile
              is  a  make(1) script that uses hpftodit(1) to prepare the groff
              font description files above from HP TFM data; in can be used to
              regenerate them in the event the TFM files are updated.

       /usr/share/groff/1.23.0/font/devlj4/generate/special.awk
              is an awk(1) script that corrects the  Intellifont‐based  height
              metrics  for several glyphs in the S (special) font for TrueType
              CG Times used in the HP LaserJet 4000 and later.

       /usr/share/groff/1.23.0/font/devlj4/generate/special.map
       /usr/share/groff/1.23.0/font/devlj4/generate/symbol.map
       /usr/share/groff/1.23.0/font/devlj4/generate/text.map
       /usr/share/groff/1.23.0/font/devlj4/generate/wingdings.map
              map MSL indices and HP Unicode PUA assignments to groff  special
              character identifiers.

See also
       groff(1), groff_diff(1), grolj4(1), groff_font(5)

groff 1.23.0                      2 July 2023                      hpftodit(1)
───────────────────────────────────────────────────────────────────────────────
indxbib(1)                  General Commands Manual                 indxbib(1)

Name
       indxbib - make inverted index for bibliographic databases

Synopsis
       indxbib [-w] [-c common‐words‐file] [-d dir] [-f list‐file]
               [-h min‐hash‐table‐size] [-i excluded‐fields]
               [-k max‐keys‐per‐record] [-l min‐key‐length] [-n threshold]
               [-o file] [-t max‐key‐length] [file ...]

       indxbib --help

       indxbib -v
       indxbib --version

Description
       indxbib makes an inverted index for the bibliographic databases in each
       file for use with refer(1), lookbib(1), and lkbib(1).  Each created in‐
       dex  is named file.i; writing is done to a temporary file which is then
       renamed to this.  If no file operands are given on the command line be‐
       cause the -f option has been used, and no -o option is given, the index
       will be named Ind.i.

       Bibliographic databases  are  divided  into  records  by  blank  lines.
       Within  a record, each field starts with a % character at the beginning
       of a line.  Fields have a one letter name that follows the % character.

       The values set by the -c, -l, -n, and -t options are stored in the  in‐
       dex:  when  the index is searched, keys will be discarded and truncated
       in a manner appropriate to these options; the  original  keys  will  be
       used  for verifying that any record found using the index actually con‐
       tains the keys.  This means that a user  of  an  index  need  not  know
       whether  these options were used in the creation of the index, provided
       that not all the keys to be searched for would have been discarded dur‐
       ing indexing and that the user supplies at least the part of  each  key
       that  would  have  remained after being truncated during indexing.  The
       value set by the -i option is also stored in the index and will be used
       in verifying records found using the index.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -c common‐words‐file
              Read  the list of common words from common‐words‐file instead of
              /usr/share/groff/1.23.0/eign.

       -d dir Use dir as the name of the directory to store in the index,  in‐
              stead  of  that returned by getcwd(2).  Typically, dir will be a
              symbolic link whose target is the current working directory.

       -f list‐file
              Read the files to be indexed from list‐file.  If list‐file is -,
              files will be read from the standard input stream.  The  -f  op‐
              tion can be given at most once.

       -h min‐hash‐table‐size
              Use the first prime number greater than or equal to the argument
              for the size of the hash table.  Larger values will usually make
              searching  faster, but will make the index file larger and cause
              indxbib to use more memory.  The default hash table size is 997.

       -i excluded‐fields
              Don’t index the contents of fields whose names are in  excluded‐
              fields.   Field names are one character each.  If this option is
              not present, indxbib excludes fields X, Y, and Z.

       -k max‐keys‐per‐record
              Use no more keys per input record than specified  in  the  argu‐
              ment.  If this option is not present, the maximum is 100.

       -l min‐key‐length
              Discard  any  key whose length in characters is shorter than the
              value of the argument.  If this option is not present, the mini‐
              mum key length is 3.

       -n threshold
              Discard the threshold most common words from  the  common  words
              file.   If this option is not present, the 100 most common words
              are discarded.

       -o basename
              Name the index basename.i.

       -t max‐key‐length
              Truncate keys to max‐key‐length in characters.  If  this  option
              is not present, keys are truncated to 6 characters.

       -w     Index whole files.  Each file is a separate record.

Files
       file.i index for file

       Ind.i  default index name

       /usr/share/groff/1.23.0/eign
              contains  the  list  of  common  words.   The  traditional name,
              “eign”, is an abbreviation of “English ignored [word list]”.

       indxbibXXXXXX
              temporary file

See also
       “Some Applications of Inverted Indexes on the Unix System”,  by  M.  E.
       Lesk,  1978,  AT&T Bell Laboratories Computing Science Technical Report
       No. 69.

       refer(1), lkbib(1), lookbib(1)

groff 1.23.0                      2 July 2023                       indxbib(1)
───────────────────────────────────────────────────────────────────────────────
lkbib(1)                    General Commands Manual                   lkbib(1)

Name
       lkbib - search bibliographic databases

Synopsis
       lkbib [-n] [-i fields] [-p file] ... [-t n] key ...

       lkbib --help

       lkbib -v
       lkbib --version

Description
       lkbib searches bibliographic databases for references  containing  key‐
       words  key  and  writes  any  references  found  to the standard output
       stream.  It reads databases given by -p options and then (unless -n  is
       given)  a  default  database.   The  default database is taken from the
       REFER environment variable if it is set,  otherwise  it  is  /usr/dict/
       papers/Ind.   For each database file to be searched, if an index file.i
       created by indxbib(1) exists, then it will be  searched  instead;  each
       index can cover multiple databases.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -i string
              When searching files for which no index exists, ignore the  con‐
              tents of fields whose names are in string.

       -n     Suppress search of default database.

       -p file
              Search file.  Multiple -p options can be used.

       -t n   Require  only  the  first n characters of keys to be given.  The
              default is 6.

Environment
       REFER  Default database.

Files
       /usr/dict/papers/Ind
              Default database to be used if the REFER environment variable is
              not set.

       file.i Index files.

See also
       “Some Applications of Inverted Indexes on the Unix System”,  by  M.  E.
       Lesk,  1978,  AT&T Bell Laboratories Computing Science Technical Report
       No. 69.

       refer(1), lookbib(1), indxbib(1)

groff 1.23.0                      2 July 2023                         lkbib(1)
───────────────────────────────────────────────────────────────────────────────
lookbib(1)                  General Commands Manual                 lookbib(1)

Name
       lookbib - search bibliographic databases

Synopsis
       lookbib [-i string] [-t n] file ...

       lookbib --help

       lookbib -v
       lookbib --version

Description
       lookbib writes a prompt to the standard error stream (unless the  stan‐
       dard  input  stream is not a terminal), reads from the standard input a
       line containing a set of keywords, searches each bibliographic database
       file for references containing those keywords,  writes  any  references
       found to the standard output stream, and repeats this process until the
       end  of  input.   For  each  database  file to be searched, if an index
       file.i created by indxbib(1) exists, then it will be searched  instead;
       each index can cover multiple databases.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -i string
              When searching files for which no index exists, ignore the  con‐
              tents of fields whose names are in string.

       -t n   Require  only  the  first n characters of keys to be given.  The
              default is 6.

Files
       file.i Index files.

See also
       “Some Applications of Inverted Indexes on the Unix System”,  by  M.  E.
       Lesk,  1978,  AT&T Bell Laboratories Computing Science Technical Report
       No. 69.

       refer(1), lkbib(1), indxbib(1)

groff 1.23.0                      2 July 2023                       lookbib(1)
───────────────────────────────────────────────────────────────────────────────
mmroff(1)                   General Commands Manual                  mmroff(1)

Name
       mmroff - cross‐referencing front end for GNU roff mm macro package

Synopsis
       mmroff [-x] groff‐argument ...

       mmroff --help

       mmroff --version

Description
       mmroff is a simple wrapper for groff, used to expand  cross  references
       in mm; see groff_mm(7).  It runs groff with the -mm option twice, first
       with  -z  and  -rRef=1 to populate cross‐reference and index files with
       their corresponding entries, and then again to  produce  the  document.
       It  also handles the inclusion of PostScript images with the PIC macro.
       Documents that do not use these features of groff mm (the  INITI,  IND,
       INDP,  INITR,  SETR,  GETHN, GETPN, GETR, GETST, and PIC macros) do not
       require mmroff.

Options
       --help displays a usage message, while --version shows version informa‐
       tion; both exit afterward.

       -x     Create or update the cross‐reference file and exit.

Authors
       mmroff was written by Jörgen Hägg ⟨jh@axis.se⟩ of Lund, Sweden.

See also
       groff_mm(7), groff_mmse(7), groff(1), troff(1), tbl(1), pic(1), eqn(1)

groff 1.23.0                      2 July 2023                        mmroff(1)
───────────────────────────────────────────────────────────────────────────────
neqn(1)                     General Commands Manual                    neqn(1)

Name
       neqn - format equations for character‐cell terminal output

Synopsis
       neqn [eqn‐argument ...]

Description
       neqn invokes the eqn(1) command with the ascii output device.

       eqn does not support low‐resolution, typewriter‐like devices,  although
       it may work adequately for very simple input.

See also
       eqn(1)

groff 1.23.0                      2 July 2023                          neqn(1)
───────────────────────────────────────────────────────────────────────────────
nroff(1)                    General Commands Manual                   nroff(1)

Name
       nroff - format documents with groff for TTY (terminal) devices

Synopsis
       nroff [-bcCEhikpRStUVz] [-d ctext] [-d string=text] [-K fallback‐
             encoding] [-m macro‐package] [-M macro‐directory] [-n page‐
             number] [-o page‐list] [-P postprocessor‐argument] [-r cnumeric‐
             expression] [-r register=numeric‐expression] [-T output‐device]
             [-w warning‐category] [-W warning‐category] [file ...]

       nroff --help

       nroff -v
       nroff --version

Description
       nroff  formats  documents  written  in  the groff(7) language for type‐
       writer‐like devices such as terminal emulators.  GNU nroff emulates the
       AT&T  nroff  command  using  groff(1).   nroff  generates  output   via
       grotty(1),  groff’s  terminal  output  driver,  which needs to know the
       character encoding scheme used by the device.  Consequently, acceptable
       arguments to the -T option are ascii, latin1,  utf8,  and  cp1047;  any
       others  are ignored.  If neither the GROFF_TYPESETTER environment vari‐
       able nor the -T command‐line option (which  overrides  the  environment
       variable)  specifies a (valid) device, nroff consults the locale to se‐
       lect an appropriate output device.  It first tries the  locale(1)  pro‐
       gram,  then  checks  several  locale‐related environment variables; see
       section “Environment” below.  If all of the foregoing fail, -Tascii  is
       implied.

       The  -b, -c, -C, -d, -E, -i, -m, -M, -n, -o, -r, -U, -w, -W, and -z op‐
       tions have the effects described in troff(1).  -c and -h  imply  “-P-c”
       and “-P-h”, respectively; -c is also interpreted directly by troff.  In
       addition,  this  implementation  ignores the AT&T nroff options -e, -q,
       and -s (which are not implemented in groff).  The options -k,  -K,  -p,
       -P, -R, -t, and -S are documented in groff(1).  -V causes nroff to dis‐
       play  the  constructed groff command on the standard output stream, but
       does not execute it.  -v and --version show version  information  about
       nroff  and the programs it runs, while --help displays a usage message;
       all exit afterward.

Exit status
       nroff exits with error status 2 if there was a problem parsing its  ar‐
       guments,  with  status  0  if  any of the options -V, -v, --version, or
       --help were specified, and with the status of groff otherwise.

Environment
       Normally, the path separator in environment variables ending with  PATH
       is the colon; this may vary depending on the operating system.  For ex‐
       ample, Windows uses a semicolon instead.

       GROFF_BIN_PATH
              is  a colon‐separated list of directories in which to search for
              the groff executable before searching in PATH.  If unset,  /usr/
              bin is used.

       GROFF_TYPESETTER
              specifies the default output device for groff.

       LC_ALL
       LC_CTYPE
       LANG
       LESSCHARSET
              are pattern‐matched in this order for contents matching standard
              character encodings supported by groff in the event no -T option
              is  given and GROFF_TYPESETTER is unset, or the values specified
              are invalid.

Files
       /usr/share/groff/1.23.0/tmac/tty-char.tmac
              defines fallback definitions of roff special characters.   These
              definitions  more  poorly  optically  approximate typeset output
              than those of tty.tmac in favor of communicating semantic infor‐
              mation.  nroff loads it automatically.

Notes
       Pager programs like more(1) and less(1) may  require  command‐line  op‐
       tions to correctly handle some output sequences; see grotty(1).

See also
       groff(1), troff(1), grotty(1), locale(1), roff(7)

groff 1.23.0                      2 July 2023                         nroff(1)
───────────────────────────────────────────────────────────────────────────────
pdfmom(1)                   General Commands Manual                  pdfmom(1)

Name
       pdfmom - produce PDF documents using the mom macro package for groff

Synopsis
       pdfmom [-Tpdf] [groff‐options] [file ...]

       pdfmom -Tps [pdfroff‐options] [groff‐options] [file ...]

       pdfmom -v
       pdfmom --version

Description
       pdfmom  is a wrapper around groff(1) that facilitates the production of
       PDF documents from files formatted with the mom macros.

       pdfmom prints to the standard output, so output must usually  be  redi‐
       rected to a destination file.  The size of the final PDF can be reduced
       by piping the output through ps2pdf(1).

       If  called  with  the  -Tpdf  option  (which  is  the  default), pdfmom
       processes files using groff’s native PDF driver, gropdf(1).  If -Tps is
       given, processing is passed over to pdfroff, which uses  groff’s  Post‐
       Script  driver.   In  either case, multiple runs of the source file are
       performed in order to satisfy any forward references in the document.

       pdfmom accepts all the same options as groff.  If -Tps  is  given,  the
       options  associated  with  pdfroff  are  accepted as well.  When pdfmom
       calls pdfroff, the options “-mpdfmark -mom --no-toc”  options  are  im‐
       plied  and should not be given on the command line.  Equally, it is not
       necessary to supply the -mom or -m mom options when -Tps is absent.

       PDF integration with the mom macros is discussed in full in the  manual
       “Producing  PDFs  with  groff  and mom”, which was itself produced with
       pdfmom.

       If called with the -v or --version options, pdfmom displays its version
       information and exits.

Authors
       pdfmom was written by Deri James ⟨deri@chuzzlewit.myzen.co.uk⟩ and  Pe‐
       ter Schaffter ⟨peter@schaffter.ca⟩, and is maintained by James.

See also
       /usr/share/doc/groff-1.23.0/pdf/mom-pdf.pdf
              “Producing  PDFs  with  groff  and mom”, by Deri James and Peter
              Schaffter.  This file, together with its source, mom-pdf.mom, is
              part of the groff distribution.

       groff(1), gropdf(1), pdfroff(1), ps2pdf(1)

groff 1.23.0                      2 July 2023                        pdfmom(1)
───────────────────────────────────────────────────────────────────────────────
pdfroff(1)                  General Commands Manual                 pdfroff(1)

Name
       pdfroff - construct files in Portable Document Format using groff

Synopsis
       pdfroff [groff‐option] [--emit-ps] [--no-toc-relocation]
               [--no-kill-null-pages] [--stylesheet=name] [--no-pdf-output]
               [--pdf-output=name] [--no-reference-dictionary]
               [--reference-dictionary=name] [--report-progress]
               [--keep-temporary-files] [file ...]

       pdfroff -h
       pdfroff --help

       pdfroff -v [groff‐option ...]
       pdfroff --version [groff‐option ...]

       groff‐option is any short option supported by groff(1) except  for  -h,
       -T, and -v; see section “Usage” below.

Description
       pdfroff is a wrapper program for the GNU text processing system, groff.
       It  transparently handles the mechanics of multiple pass groff process‐
       ing, when applied to suitably marked up groff source files,  such  that
       tables of contents and body text are formatted separately, and are sub‐
       sequently  combined  in  the  correct order, for final publication as a
       single PDF document.  A further optional “style  sheet”  capability  is
       provided;  this  allows for the definition of content which is required
       to precede the table of contents, in the published document.

       For each invocation of pdfroff, the ultimate  groff  output  stream  is
       post‐processed  by  the Ghostscript gs(1) interpreter to produce a fin‐
       ished PDF document.

       pdfroff makes no assumptions about, and imposes no restrictions on, the
       use of any groff macro packages which the user may choose to employ, in
       order to achieve a desired document format; however,  it  does  include
       specific  built  in  support  for the pdfmark macro package, should the
       user choose to employ it.  Specifically, if the pdfhref macro,  defined
       in  the pdfmark.tmac package, is used to define public reference marks,
       or dynamic links to such reference marks, then pdfroff performs as many
       preformatting groff passes as required, up to a maximum limit of  four,
       in  order to compile a document reference dictionary, to resolve refer‐
       ences, and to expand the dynamically defined content of links.

Usage
       The command line is parsed in accordance with normal  GNU  conventions,
       but  with  one exception—when specifying any short form option (i.e., a
       single character option introduced by a single hyphen), and if that op‐
       tion expects an argument,  then  it  must  be  specified  independently
       (i.e.,  it  may  not be appended to any group of other single character
       short form options).

       Long form option names (i.e., those introduced by a double hyphen)  may
       be abbreviated to their minimum length unambiguous initial substring.

       Otherwise, pdfroff usage closely mirrors that of groff itself.  Indeed,
       with  the  exception  of the -h, -v, and -T dev short form options, and
       all long form options, which are parsed internally by pdfroff, all  op‐
       tions  and file name arguments specified on the command line are passed
       on to groff, to control the formatting of  the  PDF  document.   Conse‐
       quently,  pdfroff  accepts  all  options and arguments, as specified in
       groff(1), which may also be considered as the definitive reference  for
       all standard pdfroff options and argument usage.

Options
       pdfroff  accepts  all of the short form options (i.e., those introduced
       by a single hyphen), which are available with groff  itself.   In  most
       cases,  these  are simply passed transparently to groff; the following,
       however, are handled specially by pdfroff.

       -h     Same as --help; see below.

       -i     Process standard input, after all other specified  input  files.
              This  is  passed  transparently  to  groff, but, if grouped with
              other options, it must be the first in  the  group.   Hiding  it
              within  a  group breaks standard input processing, in the multi‐
              ple‐pass groff processing context of pdfroff.

       -T dev Only -T ps is supported by pdfroff.  Attempting to  specify  any
              other device causes pdfroff to abort.

       -v     Same as --version; see below.

       See  groff(1)  for a description of all other short form options, which
       are transparently passed through pdfroff to groff.

       All long form options (i.e., those introduced by a double  hyphen)  are
       interpreted locally by pdfroff; they are not passed on to groff, unless
       otherwise stated below.

       --help Causes pdfroff to display a summary of the its usage syntax, and
              supported options, and then exit.

       --emit-ps
              Suppresses  the final output conversion step, causing pdfroff to
              emit PostScript output instead of PDF.  This may  be  useful  to
              capture  intermediate PostScript output when using a specialised
              postprocessor, such as gpresent for example, in place of the de‐
              fault Ghostscript PDF writer.

       --keep-temporary-files
              Suppresses the deletion of temporary files, which  normally  oc‐
              curs  after  pdfroff has completed PDF document formatting; this
              may be useful when debugging formatting problems.

              See section “Files” below for a  description  of  the  temporary
              files used by pdfroff.

       --no-pdf-output
              May  be  used  with  the --reference-dictionary=name option (de‐
              scribed below) to eliminate the overhead of PDF formatting  when
              running  pdfroff  to  create a reference dictionary for use in a
              different document.

       --no-reference-dictionary
              May be used to eliminate the overhead of  creating  a  reference
              dictionary,  when  it is known that the target PDF document con‐
              tains no public references, created by the pdfhref macro.

       --no-toc-relocation
              May be used to eliminate the extra groff processing pass,  which
              is  required to generate a table of contents, and relocate it to
              the start of the PDF  document,  when  processing  any  document
              which lacks an automatically generated table of contents.

       --no-kill-null-pages
              While  preparing  for  simulation  of the manual collation step,
              which is traditionally required to relocate a table of  contents
              to  the  start  of  a  document, pdfroff accumulates a number of
              empty page descriptions into the intermediate PostScript  output
              stream.   During the final collation step, these empty pages are
              normally discarded  from  the  finished  document;  this  option
              forces pdfroff to leave them in place.

       --pdf-output=name
              Specifies the name to be used for the resultant PDF document; if
              unspecified,  the  PDF  output is written to standard output.  A
              future version of pdfroff may use this  option,  to  encode  the
              document name in a generated reference dictionary.

       --reference-dictionary=name
              Specifies  the  name to be used for the generated reference dic‐
              tionary file; if unspecified, the reference dictionary  is  cre‐
              ated  in  a  temporary  file, which is deleted when pdfroff com‐
              pletes processing of the current document.  This option must  be
              specified,  if  it  is desired to save the reference dictionary,
              for use in references placed in other PDF documents.

       --report-progress
              Causes pdfroff to display an informational message  on  standard
              error, at the start of each groff processing pass.

       --stylesheet=name
              Specifies the name of an input file, to be used as a style sheet
              for  formatting of content, which is to be placed before the ta‐
              ble of contents, in the formatted PDF document.

       --version
              Causes pdfroff to display a version identification message.  The
              entire command line is then passed transparently to groff, in  a
              one  pass  operation  only,  in  order to display the associated
              groff version information, before exiting.

Environment
       The following environment variables may be set, and exported, to modify
       the behaviour of pdfroff.

       PDFROFF_COLLATE
              Specifies the program to be used for collation of  the  finished
              PDF document.

              This  collation  step may be required to move tables of contents
              to the start of the finished PDF document, when formatting  with
              traditional  macro  packages, which print them at the end.  How‐
              ever, users should not normally need to specify PDFROFF_COLLATE,
              (and indeed, are not encouraged  to  do  so).   If  unspecified,
              pdfroff uses sed(1) by default, which normally suffices.

              If  PDFROFF_COLLATE  is specified, then it must act as a filter,
              accepting a list of file name arguments, and write its output to
              the  standard  output  stream,  whence  it  is  piped   to   the
              PDFROFF_POSTPROCESSOR_COMMAND,  to produce the finished PDF out‐
              put.

              When specifying PDFROFF_COLLATE, it  is  normally  necessary  to
              also specify PDFROFF_KILL_NULL_PAGES.

              PDFROFF_COLLATE  is  ignored,  if  pdfroff  is  invoked with the
              --no-kill-null-pages option.

       PDFROFF_KILL_NULL_PAGES
              Specifies options to be passed to the PDFROFF_COLLATE program.

              It   should   not   normally    be    necessary    to    specify
              PDFROFF_KILL_NULL_PAGES.   The  internal  default  is  a  sed(1)
              script, which is intended to remove completely blank pages  from
              the  collated  output stream, and which should be appropriate in
              most applications of pdfroff.  However, if  any  alternative  to
              sed(1)  is specified for PDFROFF_COLLATE, then it is likely that
              a     corresponding      alternative      specification      for
              PDFROFF_KILL_NULL_PAGES is required.

              As  in  the  case of PDFROFF_COLLATE, PDFROFF_KILL_NULL_PAGES is
              ignored, if pdfroff is invoked with the --no-kill-null-pages op‐
              tion.

       PDFROFF_POSTPROCESSOR_COMMAND
              Specifies the command to be used for the final document  conver‐
              sion from PostScript intermediate output to PDF.  It must behave
              as  a  filter, writing its output to the standard output stream,
              and must accept an arbitrary number of files ... arguments, with
              the special case of “-” representing the standard input stream.

              If unspecified, PDFROFF_POSTPROCESSOR_COMMAND defaults to
                   gs -dBATCH -dQUIET -dNOPAUSE -dSAFER -sDEVICE=pdfwrite \
                        -sOutputFile=-

       GROFF_TMPDIR
              Identifies the directory in which pdfroff should  create  tempo‐
              rary  files.   If  GROFF_TMPDIR is not specified, then the vari‐
              ables TMPDIR, TMP and TEMP are considered in  turn  as  possible
              temporary  file  repositories.   If  none of these are set, then
              temporary files are created in the current directory.

       GROFF_GHOSTSCRIPT_INTERPRETER
              Specifies the program to be invoked when pdfroff converts  groff
              PostScript  output  to PDF.  If PDFROFF_POSTPROCESSOR_COMMAND is
              specified, then the command name it specifies is implicitly  as‐
              signed to GROFF_GHOSTSCRIPT_INTERPRETER, overriding any explicit
              setting      specified      in      the     environment.      If
              GROFF_GHOSTSCRIPT_INTERPRETER is  not  specified,  then  pdfroff
              searches the process PATH, looking for a program with any of the
              well  known  names for the Ghostscript interpreter; if no Ghost‐
              script interpreter can be found, pdfroff aborts.

       GROFF_AWK_INTERPRETER
              Specifies the program to be invoked when pdfroff  is  extracting
              reference  dictionary  entries from a groff intermediate message
              stream.  If GROFF_AWK_INTERPRETER is not specified, then pdfroff
              searches the process PATH, looking for any of the preferred pro‐
              grams, gawk, mawk, nawk, and awk, in  that  order;  if  none  of
              these  are found, pdfroff issues a warning message, and continue
              processing; however, in this case, no  reference  dictionary  is
              created.

       OSTYPE Typically  defined automatically by the operating system, OSTYPE
              is used on Microsoft Win32/MS‐DOS platforms only, to  infer  the
              default PATH_SEPARATOR character, which is used when parsing the
              process PATH to search for external helper programs.

       PATH_SEPARATOR
              If  set,  PATH_SEPARATOR overrides the default separator charac‐
              ter, (‘:’ on POSIX/Unix systems, inferred  from  OSTYPE  on  Mi‐
              crosoft  Win32/MS‐DOS),  which  is used when parsing the process
              PATH to search for external helper programs.

       SHOW_PROGRESS
              If this is set to a non‐empty value, then pdfroff always behaves
              as if the --report-progress option is specified on  the  command
              line.

Files
       Input  and  output files for pdfroff may be named according to any con‐
       vention of the user’s choice.  Typically, input files may be named  ac‐
       cording  to the choice of the principal normatting macro package, e.g.,
       file.ms might be an input file  for  formatting  using  the  ms  macros
       (s.tmac); normally, the final output file should be named file.pdf.

       Temporary  files created by pdfroff are placed in the file system hier‐
       archy, in or below the directory  specified  by  environment  variables
       (see  section  “Environment”  above).  If mktemp(1) is available, it is
       invoked to create a private subdirectory  of  the  nominated  temporary
       files  directory,  (with  subdirectory  name  derived from the template
       pdfroff-XXXXXXXXXX); if this subdirectory is successfully created,  the
       temporary files will be placed within it, otherwise they will be placed
       directly in the directory nominated in the environment.

       All  temporary  files  themselves are named according to the convention
       pdf$$.*, where $$ is  the  standard  shell  variable  representing  the
       process  identifier of the pdfroff process itself, and * represents any
       of the extensions used by pdfroff to identify the  following  temporary
       and intermediate files.

       pdf$$.tmp
              A  scratch  pad  file, used to capture reference data emitted by
              groff, during the reference dictionary compilation phase.

       pdf$$.ref
              The reference dictionary, as compiled in the last but  one  pass
              of  the reference dictionary compilation phase; (at the start of
              the first pass,  this  file  is  created  empty;  in  successive
              passes,  it  contains  the reference dictionary entries, as col‐
              lected in the preceding pass).

              If the --reference-dictionary=name option is specified, this in‐
              termediate file becomes permanent, and  is  named  name,  rather
              than pdf$$.ref.

       pdf$$.cmp
              Used  to  collect reference dictionary entries during the active
              pass of the reference dictionary compilation phase.  At the  end
              of any pass, when the content of pdf$$.cmp compares as identical
              to   pdf$$.ref,   (or   the  corresponding  file  named  by  the
              --reference-dictionary=name option), then  reference  dictionary
              compilation is terminated, and the document reference map is ap‐
              pended  to  this  intermediate  file, for inclusion in the final
              formatting passes.

       pdf$$.tc
              An intermediate PostScript file, in which  “Table  of  Contents”
              entries  are collected, to facilitate relocation before the body
              text, on ultimate output to the Ghostscript postprocessor.

       pdf$$.ps
              An intermediate PostScript file, in which the body text is  col‐
              lected  prior  to ultimate output to the Ghostscript postproces‐
              sor, in the proper sequence, after pdf$$.tc.

Authors
       pdfroff was written by Keith Marshall  ⟨keith.d.marshall@ntlworld.com⟩,
       who  maintains  it  at  his  groff‐pdfmark OSDN site ⟨https://osdn.net/
       users/keith/pf/groff‐pdfmark/wiki/FrontPage⟩.  groff’s version  may  be
       withdrawn in a future release.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       Since  pdfroff provides a superset of all groff capabilities, the above
       manual, or its terser reference page, groff(7) may also  be  considered
       definitive  references  to  all  standard capabilities of pdfroff, with
       this document providing the reference to pdfroff’s extended features.

       While pdfroff imposes neither any restriction on, nor  any  requirement
       for,  the use of any specific groff macro package, a number of supplied
       macro packages, and in particular those  associated  with  the  package
       pdfmark.tmac,  are  best  suited  for use with pdfroff as the preferred
       formatter.

       /usr/share/doc/groff-1.23.0/pdf/pdfmark.pdf
              “Portable Document Format Publishing with GNU Troff”,  by  Keith
              Marshall,  offers  detailed  documentation  on  the use of these
              packages.  This file, together with its source,  pdfmark.ms,  is
              part of the groff distribution.

groff 1.23.0                      2 July 2023                       pdfroff(1)
───────────────────────────────────────────────────────────────────────────────
pfbtops(1)                  General Commands Manual                 pfbtops(1)

Name
       pfbtops  -  translate  PostScript  Printer Font Binary files to Printer
       Font ASCII

Synopsis
       pfbtops [pfb‐file]

       pfbtops --help

       pfbtops -v
       pfbtops --version

Description
       pfbtops translates a PostScript Type 1  font  in  Printer  Font  Binary
       (PFB)  format  to  Printer  Font ASCII (PFA) format, splitting overlong
       lines in text packets into smaller chunks.  If pfb‐file is omitted, the
       PFB file will be read from the standard input  stream.   The  PFA  font
       will  be  written  on the standard output stream.  PostScript fonts for
       MS‐DOS were historically supplied in PFB format.  Use of  a  PostScript
       Type 1 font with groff requires conversion of its metrics (AFM file) to
       a groff font description file; see afmtodit(1).

       The --help option displays a usage message, while -v and --version show
       version information; all exit afterward.

See also
       grops(1), gropdf(1)

groff 1.23.0                      2 July 2023                       pfbtops(1)
───────────────────────────────────────────────────────────────────────────────
pic(1)                      General Commands Manual                     pic(1)

Name
       pic - compile pictures for troff or TeX

Synopsis
       pic [-CnSU] [file ...]

       pic -t [-cCSUz] [file ...]

       pic --help

       pic -v
       pic --version

Description
       The  GNU implementation of pic is part of the groff(1) document format‐
       ting system.  pic is a troff(1) preprocessor that  translates  descrip‐
       tions  of  diagrammatic pictures embedded in roff(7) or TeX input files
       into the language understood by TeX or troff.  It copies  the  contents
       of  each  file to the standard output stream, except that lines between
       .PS and any of .PE, .PF, or .PY are interpreted as picture descriptions
       in the pic language.  End a pic picture with .PE to leave  the  drawing
       position  at the bottom of the picture, and with .PF or .PY to leave it
       at the top.  Normally, pic is not executed directly by  the  user,  but
       invoked  by  specifying the -p option to groff(1).  If no file operands
       are given on the command line, or if file is “-”,  the  standard  input
       stream is read.

       It  is  the user’s responsibility to provide appropriate definitions of
       the PS, PE, and one or both of the PF and  PY  macros.   When  a  macro
       package does not supply these, obtain simple definitions with the groff
       option -mpic; these will center each picture.

       GNU pic supports PY as a synonym of PF to work around a name space col‐
       lision  with  the  mm  macro package, which defines PF as a page footer
       management macro.  Use PF preferentially unless a similar problem faces
       your document.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -c     Be  more compatible with tpic; implies -t.  Lines beginning with
              \ are not passed through transparently.  Lines beginning with  .
              are  passed through with the initial . changed to \.  A line be‐
              ginning with .ps is given special treatment:  it  takes  an  op‐
              tional integer argument specifying the line thickness (pen size)
              in  milliinches;  a  missing argument restores the previous line
              thickness; the default line thickness  is  8  milliinches.   The
              line thickness thus specified takes effect only when a non‐nega‐
              tive  line  thickness  has  not  been  specified  by  use of the
              thickness attribute or by setting the linethick variable.

       -C     Recognize .PS, .PE, .PF, and .PY even when followed by a charac‐
              ter other than space or newline.

       -n     Don’t use groff extensions to the troff drawing commands.  Spec‐
              ify this option if a postprocessor you’re using doesn’t  support
              these  extensions,  described in groff_out(5).  This option also
              causes pic not to use zero‐length lines to draw  dots  in  troff
              mode.

       -S     Operate  in safer mode; sh commands are ignored.  This mode, en‐
              abled by default, can be useful when operating on  untrustworthy
              input.

       -t     Produce TeX output.

       -U     Operate in unsafe mode; sh commands are interpreted.

       -z     In TeX mode, draw dots using zero‐length lines.

       The following options supported by other versions of pic are ignored.

       -D     Draw  all  lines  using  the \D escape sequence.  GNU pic always
              does this.

       -T dev Generate output for the troff device dev.  This  is  unnecessary
              because the troff output generated by GNU pic is device‐indepen‐
              dent.

Usage
       This  section  primarily  discusses the differences between GNU pic and
       the Eighth Edition Research Unix version of AT&T pic (1985).   Many  of
       these differences also apply to later versions of AT&T pic.

   TeX mode
       TeX‐compatible output is produced when the -t option is specified.  You
       must use a TeX driver that supports tpic version 2 specials.  (tpic was
       a  fork  of  AT&T  pic by Tim Morgan of the University of California at
       Irvine that diverged from its source around 1984.  It is best known to‐
       day for lending its name to a group of \special  commands  it  produced
       for TeX.)

       Lines  beginning  with \ are passed through transparently; a % is added
       to the end of the line to avoid unwanted spaces.  You  can  safely  use
       this  feature  to change fonts or the value of \baselineskip.  Anything
       else may well produce undesirable results; use at your  own  risk.   By
       default,  lines  beginning with a dot are not treated specially—but see
       the -c option.

       In TeX mode, pic will define a vbox called  \graph  for  each  picture.
       Use GNU pic’s figname command to change the name of the vbox.  You must
       print that vbox yourself using the command
              \centerline{\box\graph}
       for  instance.  Since the vbox has a height of zero (it is defined with
       \vtop) this will produce slightly more vertical space above the picture
       than below it;
              \centerline{\raise 1em\box\graph}
       would avoid this.  To give the vbox a positive height and  a  depth  of
       zero  (as used by LaTeX’s graphics.sty, for example) define the follow‐
       ing macro in your document.
              \def\gpicbox#1{%
                \vbox{\unvbox\csname #1\endcsname\kern 0pt}}
       You can then simply say \gpicbox{graph} instead of \box\graph.

   Commands
       Several commands new to GNU pic accept delimiters, shown in their  syn‐
       opses  as braces { }.  Nesting of braces is supported.  Any other char‐
       acters (except a space, tab, or newline) may be used as alternative de‐
       limiters, in which case the members of a given pair must be  identical.
       Strings  are recognized within delimiters of either kind; they may con‐
       tain the delimiter character or unbalanced braces.

       for variable = expr1 to expr2 [by [*]expr3] do X body X
              Set variable to expr1.  While the value of variable is less than
              or equal to expr2, do body and increment variable by  expr3;  if
              by  is not given, increment variable by 1.  If expr3 is prefixed
              by * then variable will instead be  multiplied  by  expr3.   The
              value  of  expr3 can be negative for the additive case; variable
              is then tested whether it is greater than  or  equal  to  expr2.
              For  the  multiplicative  case, expr3 must be greater than zero.
              If the constraints aren’t met, the loop isn’t executed.   X  can
              be any character not occurring in body.

       if expr then X if‐true X [else Y if‐false Y]
              Evaluate  expr;  if it is non‐zero then do if‐true, otherwise do
              if‐false.  X can be any character not occurring in  if‐true.   Y
              can be any character not occurring in if‐false.

       print arg ...
              Concatenate  and  write  arguments  to the standard error stream
              followed by a newline.  Each arg must be an expression, a  posi‐
              tion, or text.  This is useful for debugging.

       command arg ...
              Concatenate  arguments  and pass them as a line to troff or TeX.
              Each arg must be an expression, a position,  or  text.   command
              allows  the  values of pic variables to be passed to the format‐
              ter.  For example,
                     .PS
                     x = 14
                     command ".ds string x is " x "."
                     .PE
                     \*[string]
              produces
                     x is 14.
              when formatted with troff.

       sh X command X
              Pass command to a shell.

       copy "filename"
              Include filename at this point in the file.

       copy ["filename"] thru X body X [until "word"]
       copy ["filename"] thru macro [until "word"]
              This construct does body once for each  line  of  filename;  the
              line  is split into blank‐delimited words, and occurrences of $i
              in body, for i between 1 and 9, are replaced by the i‐th word of
              the line.  If filename is not given, lines are  taken  from  the
              current input up to .PE.  If an until clause is specified, lines
              will  be read only until a line the first word of which is word;
              that line will then be discarded.  X can be  any  character  not
              occurring in body.  For example,
                     .PS
                     copy thru % circle at ($1,$2) % until "END"
                     1 2
                     3 4
                     5 6
                     END
                     box
                     .PE
              and
                     .PS
                     circle at (1,2)
                     circle at (3,4)
                     circle at (5,6)
                     box
                     .PE
              are  equivalent.  The commands to be performed for each line can
              also be taken from a macro defined earlier by giving the name of
              the macro as the argument to thru.  The argument after  thru  is
              looked up as a macro name first; if not defined, its first char‐
              acter is interpreted as a delimiter.

       reset
       reset pvar1[,] pvar2 ...
              Reset  predefined  variables  pvar1,  pvar2 ... to their default
              values; if no arguments are given, reset  all  predefined  vari‐
              ables  to their default values.  Variable names may be separated
              by commas, spaces, or both.  Assigning a  value  to  scale  also
              causes  all  predefined  variables that control dimensions to be
              reset to their default values times the new value of scale.

       plot expr ["text"]
              This is a text object which is constructed by using  text  as  a
              format  string for sprintf with an argument of expr.  If text is
              omitted a format string of "%g"  is  used.   Attributes  can  be
              specified  in the same way as for a normal text object.  Be very
              careful that you specify an appropriate format string; pic  does
              only very limited checking of the string.  This is deprecated in
              favour of sprintf.

       var := expr
              This syntax resembles variable assignment with = except that var
              must  already be defined, and expr will be assigned to var with‐
              out creating a variable local to the current  block.   (By  con‐
              trast,  =  defines var in the current block if it is not already
              defined there, and then changes the value in the  current  block
              only.)  For example,
                     .PS
                     x = 3
                     y = 3
                     [
                     x := 5
                     y = 5
                     ]
                     print x   y
                     .PE
              writes
                     5 3
              to the standard error stream.

   Expressions
       The syntax for expressions has been significantly extended.

       x ^ y (exponentiation)
       sin(x)
       cos(x)
       atan2(y, x)
       log(x) (base 10)
       exp(x) (base 10, i.e. 10^x)
       sqrt(x)
       int(x)
       rand() (return a random number between 0 and 1)
       rand(x) (return a random number between 1 and x; deprecated)
       srand(x) (set the random number seed)
       max(e1, e2)
       min(e1, e2)
       !e
       e1 && e2
       e1 || e2
       e1 == e2
       e1 != e2
       e1 >= e2
       e1 > e2
       e1 <= e2
       e1 < e2
       "str1" == "str2"
       "str1" != "str2"

       String comparison expressions must be parenthesised in some contexts to
       avoid ambiguity.

   Other changes
       A  bare  expression, expr, is acceptable as an attribute; it is equiva‐
       lent to dir expr, where dir is the current direction.  For example

              line 2i

       means draw a line 2 inches long in the current direction.  The ‘i’  (or
       ‘I’)  character  is  ignored;  to use another measurement unit, set the
       scale variable to an appropriate value.

       The maximum width and height of the picture are taken  from  the  vari‐
       ables maxpswid and maxpsht.  Initially, these have values 8.5 and 11.

       Scientific notation is allowed for numbers.  For example

              x = 5e-2

       Text attributes can be compounded.  For example,

              "foo" above ljust

       is valid.

       There  is  no  limit to the depth to which blocks can be examined.  For
       example,

              [A: [B: [C: box ]]] with .A.B.C.sw at 1,2
              circle at last [].A.B.C

       is acceptable.

       Arcs now have compass points determined by the circle of which the  arc
       is a part.

       Circles,  ellipses,  and  arcs  can  be  dotted or dashed.  In TeX mode
       splines can be dotted or dashed also.

       Boxes can have rounded corners.  The rad attribute specifies the radius
       of the quarter‐circles at each corner.  If no rad or diam attribute  is
       given, a radius of boxrad is used.  Initially, boxrad has a value of 0.
       A box with rounded corners can be dotted or dashed.

       Boxes  can have slanted sides.  This effectively changes the shape of a
       box from a rectangle to an arbitrary parallelogram.  The  xslanted  and
       yslanted attributes specify the x and y offset of the box’s upper right
       corner from its default position.

       The .PS line can have a second argument specifying a maximum height for
       the  picture.   If the width of zero is specified the width will be ig‐
       nored in computing the scaling factor for the picture.   GNU  pic  will
       always  scale  a picture by the same amount vertically as well as hori‐
       zontally.  This is different from DWB 2.0 pic which may scale a picture
       by a different amount vertically than horizontally if a height is spec‐
       ified.

       Each text object has an invisible box associated with it.  The  compass
       points  of  a text object are determined by this box.  The implicit mo‐
       tion associated with the object is also determined by  this  box.   The
       dimensions  of this box are taken from the width and height attributes;
       if the width attribute is not supplied then the width will be taken  to
       be  textwid;  if  the  height attribute is not supplied then the height
       will be taken to be the number of text strings associated with the  ob‐
       ject times textht.  Initially, textwid and textht have a value of 0.

       In  (almost  all) places where a quoted text string can be used, an ex‐
       pression of the form

              sprintf("format", arg, ...)

       can also be used; this will produce the arguments  formatted  according
       to format, which should be a string as described in printf(3) appropri‐
       ate for the number of arguments supplied.  Only the modifiers “#”, “-”,
       “+”,  and  “  ” [space]), a minimum field width, an optional precision,
       and the conversion specifiers %e, %E, %f, %g, %G, and %% are supported.

       The thickness of the lines used to draw objects is  controlled  by  the
       linethick  variable.   This  gives the thickness of lines in points.  A
       negative value means use the default thickness:  in  TeX  output  mode,
       this  means  use  a thickness of 8 milliinches; in TeX output mode with
       the -c option, this means use  the  line  thickness  specified  by  .ps
       lines; in troff output mode, this means use a thickness proportional to
       the pointsize.  A zero value means draw the thinnest possible line sup‐
       ported  by  the output device.  Initially, it has a value of -1.  There
       is also a thick[ness] attribute.  For example,

              circle thickness 1.5

       would draw a circle using a line with a thickness of 1.5  points.   The
       thickness  of lines is not affected by the value of the scale variable,
       nor by the width or height given in the .PS line.

       Boxes (including boxes with rounded corners or slanted sides),  circles
       and  ellipses  can  be  filled by giving them an attribute of fill[ed].
       This takes an optional argument of an expression with a value between 0
       and 1; 0 will fill it with white, 1 with black, values in between  with
       a  proportionally gray shade.  A value greater than 1 can also be used:
       this means fill with the shade of gray that is currently being used for
       text and lines.  Normally this will be black, but  output  devices  may
       provide  a  mechanism for changing this.  Without an argument, then the
       value of the variable fillval will be  used.   Initially,  this  has  a
       value  of  0.5.  The invisible attribute does not affect the filling of
       objects.  Any text associated with a filled object will be added  after
       the  object  has  been filled, so that the text will not be obscured by
       the filling.

       Additional modifiers are available to draw colored objects:  outline[d]
       sets  the color of the outline, shaded the fill color, and colo[u]r[ed]
       sets both.  All expect a  subsequent  string  argument  specifying  the
       color.
              circle shaded "green" outline "black"
       Color  is  not  yet  supported  in  TeX  mode.  Device macro files like
       ps.tmac declare color names; you can define additional  ones  with  the
       defcolor request (see groff(7)).

       To  change  the  name  of the vbox in TeX mode, set the pseudo‐variable
       figname (which is actually a specially parsed command)  within  a  pic‐
       ture.  Example:

              .PS
              figname = foobar;
              ...
              .PE

       The picture is then available in the box \foobar.

       pic  assumes  that  at  the  beginning of a picture both glyph and fill
       color are set to the default value.

       Arrow heads will be drawn as solid triangles if the variable  arrowhead
       is  non‐zero  and  either  TeX mode is enabled or the -n option has not
       been given.  Initially, arrowhead has a value of 1.  Solid arrow  heads
       are always filled with the current outline color.

       The troff output of pic is device‐independent.  The -T option is there‐
       fore  redundant.   All  numbers  are taken to be in inches; numbers are
       never interpreted to be in troff machine units.

       Objects can have an aligned attribute.  This  will  only  work  if  the
       postprocessor  is  grops(1)  or gropdf(1).  Any text associated with an
       object having the aligned attribute will be rotated about the center of
       the object so that it is aligned in the direction from the start  point
       to  the end point of the object.  This attribute will have no effect on
       objects whose start and end points are coincident.

       In places where nth is allowed, 'expr'th is also allowed.  “'th“  is  a
       single  token: no space is allowed between the apostrophe and the “th”.
       For example,

              for i = 1 to 4 do {
                 line from 'i'th box.nw to 'i+1'th box.se
              }

Conversion
       To obtain a stand‐alone picture from a pic file, enclose your pic  code
       with  .PS and .PE requests; roff configuration commands may be added at
       the beginning of the file, but no roff text.

       It is necessary to feed this file into groff without  adding  any  page
       information,  so you must check which .PS and .PE requests are actually
       called.  For example, the mm macro package adds a page number, which is
       very annoying.  At the moment, calling standard groff without any macro
       package works.  Alternatively, you can define your own requests,  e.g.,
       to do nothing:

              .de PS
              ..
              .de PE
              ..

       groff  itself  does  not  provide direct conversion into other graphics
       file formats.  But there are lots of possibilities if you first  trans‐
       form  your picture into PostScript® format using the groff option -Tps.
       Since this ps‐file lacks BoundingBox information it is not very  useful
       by  itself,  but  it may be fed into other conversion programs, usually
       named ps2other or pstoother or the like.  Moreover, the PostScript  in‐
       terpreter  Ghostscript (gs(1)) has built‐in graphics conversion devices
       that are called with the option

              gs -sDEVICE=<devname>

       Call

              gs --help

       for a list of the available devices.

       An alternative may be to use the -Tpdf option to convert  your  picture
       directly  into  PDF  format.   The MediaBox of the file produced can be
       controlled by passing a -P-p papersize to groff.

       As the Encapsulated PostScript File Format EPS is getting more and more
       important, and the conversion wasn’t regarded trivial in the  past  you
       might  be  interested  to  know  that  there is a conversion tool named
       ps2eps which does the right job.  It  is  much  better  than  the  tool
       ps2epsi packaged with gs.

       For  bitmapped  graphic  formats, you should use pstopnm; the resulting
       (intermediate) pnm(5) file can  be  then  converted  to  virtually  any
       graphics format using the tools of the netpbm package.

Files
       /usr/share/groff/1.23.0/tmac/pic.tmac
              offers simple definitions of the PS, PE, PF, and PY macros.

Bugs
       Characters  that  are invalid as input to GNU troff (see the groff Tex‐
       info manual or groff_char(7) for a list) are rejected even in TeX mode.

       The interpretation of fillval is incompatible with  the  pic  in  Tenth
       Edition Research Unix, which interprets 0 as black and 1 as white.

See also
       /usr/share/doc/groff-1.23.0/pic.ps
              “Making  Pictures with GNU pic”, by Eric S. Raymond.  This file,
              together with its source, pic.ms, is part of the groff distribu‐
              tion.

       “PIC—A Graphics Language for Typesetting: User  Manual”,  by  Brian  W.
       Kernighan,  1984  (revised 1991), AT&T Bell Laboratories Computing Sci‐
       ence Technical Report No. 116

       ps2eps is  available  from  CTAN  mirrors,  e.g.,  ⟨ftp://ftp.dante.de/
       tex-archive/support/ps2eps/⟩

       W. Richard Stevens, Turning PIC into HTML ⟨http://www.kohala.com/start/
       troff/pic2html.html⟩

       W.  Richard  Stevens,  Examples  of  pic Macros ⟨http://www.kohala.com/
       start/troff/pic.examples.ps⟩

       troff(1),   groff_out(5),   tex(1),   gs(1),   ps2eps(1),   pstopnm(1),
       ps2epsi(1), pnm(5)

groff 1.23.0                      2 July 2023                           pic(1)
───────────────────────────────────────────────────────────────────────────────
pic2graph(1)                General Commands Manual               pic2graph(1)

Name
       pic2graph - convert a pic diagram into a cropped image

Synopsis
       pic2graph [-unsafe] [-format output‐format] [-eqn delimiters] [convert‐
                 argument ...]

       pic2graph --help

       pic2graph -v
       pic2graph --version

Description
       pic2graph  reads a pic(1) program from the standard input and writes an
       image file, by default in Portable Network Graphics  (PNG)  format,  to
       the  standard  output.  It furthermore translates eqn(1) constructs, so
       it can be used for generating images of mathematical formulae.

       The input PIC code should not be  wrapped  with  the  .PS  and  .PE/.PF
       macros that normally guard it within groff(1) documents.

       Arguments  not recognized by pic2graph are passed to the ImageMagick or
       GraphicsMagick program convert(1).  By specifying these, you  can  give
       your  image  a  border, set the image’s pixel density, or perform other
       useful transformations.

       The output image is clipped using convert’s -trim option to the  small‐
       est possible bounding box that contains all the black pixels.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -eqn delimiters
              Use delimiters as the opening and closing  characters  that  de‐
              limit  eqn directives; the default is “$$”.  The option argument
              delimiters should be a two‐character string, but an empty string
              ("") is accepted as a directive to disable eqn processing.

       -format output‐format
              Write the image in output‐format, which must  be  understood  by
              convert; the default is PNG.

       -unsafe
              Run groff in unsafe mode, enabling the PIC command sh to execute
              arbitrary  Unix  shell commands.  The groff default is to forbid
              this.

Environment
       GROFF_TMPDIR
       TMPDIR
       TMP
       TEMP   These environment variables are searched in the given  order  to
              determine  the  directory where temporary files will be created.
              If none are set, /tmp is used.

Authors
       pic2graph was written by Eric S. Raymond ⟨esr@thyrsus.com⟩, based on  a
       recipe by W. Richard Stevens.

See also
       W. Richard Stevens, Turning PIC into HTML ⟨http://www.kohala.com/start/
       troff/pic2html.html⟩

       eqn2graph(1), grap2graph(1), pic(1), eqn(1), groff(1), convert(1)

groff 1.23.0                      2 July 2023                     pic2graph(1)
───────────────────────────────────────────────────────────────────────────────
preconv(1)                  General Commands Manual                 preconv(1)

Name
       preconv - prepare files for typesetting with groff

Synopsis
       preconv [-dr] [-D fallback‐encoding] [-e encoding] [file ...]

       preconv -h
       preconv --help

       preconv -v
       preconv --version

Description
       preconv  reads  each  file,  converts  its encoded characters to a form
       troff(1) can interpret, and sends the result  to  the  standard  output
       stream.   Currently, this means that code points in the range 0–127 (in
       US‐ASCII, ISO 8859, or Unicode) remain as‐is and the remainder are con‐
       verted to the groff special character form “\[uXXXX]”, where XXXX is  a
       hexadecimal  number  of  four  to six digits corresponding to a Unicode
       code point.  By default, preconv also inserts a roff .lf request at the
       beginning of each file, identifying it for the benefit  of  later  pro‐
       cessing  (including diagnostic messages); the -r option suppresses this
       behavior.

       In typical usage scenarios, preconv need not be run  directly;  instead
       it  should  be  invoked with the -k or -K options of groff.  If no file
       operands are given on the command line, or if file is “-”, the standard
       input stream is read.

       preconv tries to find the input encoding with the following  algorithm,
       stopping at the first success.

       1.  If the input encoding has been explicitly specified with option -e,
           use it.

       2.  If  the  input starts with a Unicode Byte Order Mark, determine the
           encoding as UTF‐8, UTF‐16, or UTF‐32 accordingly.

       3.  If the input stream is seekable, check the first and  second  input
           lines  for  a  recognized GNU Emacs file‐local variable identifying
           the character encoding, here referred to as the  “coding  tag”  for
           brevity.  If found, use it.

       4.  If  the  input  stream  is seekable, and if the uchardet library is
           available on the system, use it to try to infer the encoding of the
           file.

       5.  If the -D option specifies an encoding, use it.

       6.  Use the encoding specified by the current locale (LC_CTYPE), unless
           the locale is “C”, “POSIX”, or empty, in which case assume  Latin‐1
           (ISO 8859‐1).

       The  coding tag and uchardet methods in the above procedure rely upon a
       seekable input stream; when preconv reads from a pipe,  the  stream  is
       not  seekable,  and  these detection methods are skipped.  If character
       encoding detection of your input files is unreliable, arrange  for  one
       of the other methods to succeed by using preconv’s -D or -e options, or
       by  configuring  your  locale  appropriately.   groff  also  supports a
       GROFF_ENCODING environment variable, which can be overridden by its  -K
       option.   Valid  values for (or parameters to) all of these are enumer‐
       ated in the lists of recognized coding tags in the next subsection, and
       are further influenced by iconv library support.

   Coding tags
       Text editors that support more than a single  character  encoding  need
       tags  within  the input files to mark the file’s encoding.  While it is
       possible to guess the right input encoding with the help of  heuristics
       that  are  reliable for a preponderance of natural language texts, they
       are not absolutely reliable.  Heuristics can fail on  inputs  that  are
       too short or don’t represent a natural language.

       Consequently,  preconv  supports  the  coding  tag  convention  used by
       GNU Emacs (with some restrictions).  This notation appears in specially
       marked regions of an input file designated for “file‐local variables”.

       preconv interprets the following syntax if it occurs in a roff  comment
       in the first or second line of the input file.  Both “\"” and “\#” com‐
       ment  forms are recognized, but the control (or no‐break control) char‐
       acter must be the default and must begin the line.  Similarly, the  es‐
       cape character must be the default.
              -*- [...;] coding: encoding[; ...] -*-

       The  only  variable  preconv interprets is “coding”, which can take the
       values listed below.

       The following list comprises all MIME “charset” parameter values recog‐
       nized, case‐insensitively, by preconv.
              big5, cp1047, euc-jp, euc-kr,  gb2312,  iso-8859-1,  iso-8859-2,
              iso-8859-5,  iso-8859-7,  iso-8859-9,  iso-8859-13, iso-8859-15,
              koi8-r, us-ascii, utf-8, utf-16, utf-16be, utf-16le

       In addition, the following list of other  coding  tags  is  recognized,
       each of which is mapped to an appropriate value from the list above.
              ascii,  chinese-big5,  chinese-euc,  chinese-iso-8bit,  cn-big5,
              cn-gb,     cn-gb-2312,     cp878,     csascii,      csisolatin1,
              cyrillic-iso-8bit,  cyrillic-koi8, euc-china, euc-cn, euc-japan,
              euc-japan-1990,   euc-korea,   greek-iso-8bit,   iso-10646/utf8,
              iso-10646/utf-8,    iso-latin-1,    iso-latin-2,    iso-latin-5,
              iso-latin-7, iso-latin-9, japanese-euc, japanese-iso-8bit, jis8,
              koi8, korean-euc,  korean-iso-8bit,  latin-0,  latin1,  latin-1,
              latin-2,  latin-5,  latin-7,  latin-9,  mule-utf-8, mule-utf-16,
              mule-utf-16be,   mule-utf-16-be,   mule-utf-16be-with-signature,
              mule-utf-16le,   mule-utf-16-le,   mule-utf-16le-with-signature,
              utf8,            utf-16-be,            utf-16-be-with-signature,
              utf-16be-with-signature,   utf-16-le,  utf-16-le-with-signature,
              utf-16le-with-signature

       Trailing “-dos”, “-unix”, and “-mac” suffixes on coding tags (which in‐
       dicate the end‐of‐line convention used in the file) are disregarded for
       the purpose of comparison with the above tags.

   iconv support
       While preconv recognizes all of the coding tags listed above, it is ca‐
       pable on its own of interpreting only three  encodings:  Latin‐1,  code
       page  1047,  and UTF‐8.  If iconv support is configured at compile time
       and available at run time, all others are passed to iconv library func‐
       tions, which may recognize many additional encoding strings.  The  com‐
       mand “preconv -v” discloses whether iconv support is configured.

       The use of iconv means that characters in the input that encode invalid
       code  points for that encoding may be dropped from the output stream or
       mapped to the Unicode replacement character (U+FFFD).  Compare the fol‐
       lowing examples using the input “café” (note the “e” with an acute  ac‐
       cent), which due to its short length challenges inference of the encod‐
       ing used.
              printf 'caf\351\n' | LC_ALL=en_US.UTF-8 preconv
              printf 'caf\351\n' | preconv -e us-ascii
              printf 'caf\351\n' | preconv -e latin-1
       The  fate  of  the  accented  “e”  differs in each case.  In the first,
       uchardet fails to detect an encoding (though the library on your system
       may behave differently) and preconv falls back to the locale  settings,
       where  octal 351 starts an incomplete UTF‐8 sequence and results in the
       Unicode replacement character.  In the  second,  it  is  not  a  repre‐
       sentable  character  in  the declared input encoding of US‐ASCII and is
       discarded by iconv.  In the last, it is correctly detected and mapped.

   Limitations
       preconv cannot perform any transformation on input that it cannot  see.
       Examples  include files that are interpolated by preprocessors that run
       subsequently, including  soelim(1);  files  included  by  troff  itself
       through  “so”  and  similar  requests; and string definitions passed to
       troff through its -d command‐line option.

       preconv assumes that its input uses the  default  escape  character,  a
       backslash \, and writes special character escape sequences accordingly.

Options
       -h and --help display a usage message, while -v and --version show ver‐
       sion information; all exit afterward.

       -d     Emit debugging messages to the standard error stream.

       -D fallback‐encoding
              Report fallback‐encoding if all detection methods fail.

       -e encoding
              Skip detection and assume encoding; see groff’s -K option.

       -r     Write files “raw”; do not add .lf requests.

See also
       groff(1), iconv(3), locale(7)

groff 1.23.0                      2 July 2023                       preconv(1)
───────────────────────────────────────────────────────────────────────────────
refer(1)                    General Commands Manual                   refer(1)

Name
       refer - process bibliographic references for groff

Synopsis
       refer [-bCenPRS] [-a n] [-B field.macro] [-c fields] [-f n] [-i fields]
             [-k field] [-l range‐expression] [-p database‐file] [-s fields]
             [-t n] [file ...]

       refer --help

       refer -v
       refer --version

Description
       The  GNU  implementation of refer is part of the groff(1) document for‐
       matting system.  refer is a troff(1) preprocessor that prepares bibilo‐
       graphic citations by looking up keywords specified in a  roff(7)  input
       document,  obviating  the need to type such annotations, and permitting
       the citation style in formatted output to be altered independently  and
       systematically.   It  copies  the contents of each file to the standard
       output stream, except that it interprets lines between .[ and .] as ci‐
       tations to be translated into groff input, and lines  between  .R1  and
       .R2  as instructions regarding how citations are to be processed.  Nor‐
       mally, refer is not executed directly by the user, but invoked by spec‐
       ifying the -R option to groff(1).  If no file operands are given on the
       command line, or if file is “-”, the standard input stream is read.

       Each citation specifies a reference.  The citation can specify a refer‐
       ence that is contained in a bibliographic database by giving a  set  of
       keywords that only that reference contains.  Alternatively it can spec‐
       ify a reference by supplying a database record in the citation.  A com‐
       bination of these alternatives is also possible.

       For  each  citation,  refer  can produce a mark in the text.  This mark
       consists of some label which can be separated from the  text  and  from
       other  labels  in  various  ways.   For  each reference it also outputs
       groff(7) language commands that can be used by a macro package to  pro‐
       duce a formatted reference for each citation.  The output of refer must
       therefore  be processed using a suitable macro package, such as me, mm,
       mom, or ms.  The commands to format a citation’s reference can be  out‐
       put  immediately  after  the citation, or the references may be accumu‐
       lated, and the commands output at some later point.  If the  references
       are  accumulated,  then  multiple  citations of the same reference will
       produce a single formatted reference.

       The interpretation of lines between .R1 and .R2 as  prepreocessor  com‐
       mands  is a feature of GNU refer.  Documents making use of this feature
       can still be processed by AT&T refer just by adding the lines
              .de R1
              .ig R2
              ..
       to the beginning of the document.  This will cause troff(1)  to  ignore
       everything  between  .R1 and .R2.  The effect of some commands can also
       be achieved by options.  These options are supported mainly for compat‐
       ibility with AT&T refer.  It is usually more  convenient  to  use  com‐
       mands.

       refer  generates  .lf  requests  so that file names and line numbers in
       messages produced by commands that read refer output will  be  correct;
       it also interprets lines beginning with .lf so that file names and line
       numbers in the messages and .lf lines that it produces will be accurate
       even if the input has been preprocessed by a command such as soelim(1).

   Bibliographic databases
       The  bibliographic  database is a text file consisting of records sepa‐
       rated by one or more blank lines.  Within each record fields start with
       a % at the beginning of a line.  Each field has a  one  character  name
       that immediately follows the %.  It is best to use only upper and lower
       case  letters for the names of fields.  The name of the field should be
       followed by exactly one space, and then by the contents of  the  field.
       Empty fields are ignored.  The conventional meaning of each field is as
       follows:

       %A     The  name  of  an author.  If the name contains a suffix such as
              “Jr.”, it should be separated from the last  name  by  a  comma.
              There can be multiple occurrences of the %A field.  The order is
              significant.   It is a good idea always to supply an %A field or
              a %Q field.

       %B     For an article that is part of a book, the title of the book.

       %C     The place (city) of publication.

       %D     The date of publication.  The year should be specified in  full.
              If  the  month  is specified, the name rather than the number of
              the month should be used, but only the first three  letters  are
              required.  It is a good idea always to supply a %D field; if the
              date  is  unknown,  a  value  such as in press or unknown can be
              used.

       %E     For an article that is part of a book, the name of an editor  of
              the  book.  Where the work has editors and no authors, the names
              of the editors should be given as %A fields  and  “,  (ed.)”  or
              “, (eds.)” should be appended to the last author.

       %G     U.S. government ordering number.

       %I     The publisher (issuer).

       %J     For an article in a journal, the name of the journal.

       %K     Keywords to be used for searching.

       %L     Label.

       %N     Journal issue number.

       %O     Other  information.   This  is usually printed at the end of the
              reference.

       %P     Page number.  A range of pages can be specified as m-n.

       %Q     The name of the author, if the author is  not  a  person.   This
              will  only be used if there are no %A fields.  There can only be
              one %Q field.

       %R     Technical report number.

       %S     Series name.

       %T     Title.  For an article in a book or journal, this should be  the
              title of the article.

       %V     Volume number of the journal or book.

       %X     Annotation.

       For  all  fields except %A and %E, if there is more than one occurrence
       of a particular field in a record, only the last  such  field  will  be
       used.

       If  accent strings are used, they should follow the character to be ac‐
       cented.  This means that an ms document must call the .AM macro when it
       initializes.  Accent strings should not be quoted:  use  one  \  rather
       than  two.   Accent strings are an obsolescent feature of the me and ms
       macro packages; modern documents should use groff special character es‐
       cape sequences instead; see groff_char(7).

   Citations
       Citations have a characteristic format.
              .[opening‐text
              flags keywords
              fields
              .]closing‐text

       The opening‐text, closing‐text,  and  flags  components  are  optional.
       Only one of the keywords and fields components need be specified.

       The keywords component says to search the bibliographic databases for a
       reference  that  contains all the words in keywords.  It is an error if
       more than one reference is found.

       The fields components specifies additional fields to replace or supple‐
       ment those specified in the reference.  When references are being accu‐
       mulated and the keywords component is non‐empty, then additional fields
       should be specified only on the first occasion that a particular refer‐
       ence is cited, and will apply to all citations of that reference.

       The opening‐text and closing‐text components specify strings to be used
       to bracket the label instead of those in the bracket-label command.  If
       either of these components is non‐empty, the strings specified  in  the
       bracket-label  command  will  not be used; this behavior can be altered
       using the [ and ] flags.  Leading and trailing spaces  are  significant
       for these components.

       The  flags  component  is a list of non‐alphanumeric characters each of
       which modifies the treatment of this particular citation.   AT&T  refer
       will  treat these flags as part of the keywords and so will ignore them
       since they are non‐alphanumeric.  The  following  flags  are  currently
       recognized.

       #      Use  the  label specified by the short-label command, instead of
              that specified by the label command.  If no short label has been
              specified, the normal label will be used.  Typically  the  short
              label  is  used with author‐date labels and consists of only the
              date and possibly a disambiguating letter; the “#”  is  supposed
              to be suggestive of a numeric type of label.

       [      Precede  opening‐text  with  the  first  string specified in the
              bracket-label command.

       ]      Follow closing‐text with the  second  string  specified  in  the
              bracket-label command.

       An  advantage  of  using  the  [  and ] flags rather than including the
       brackets in opening‐text and closing‐text is that you  can  change  the
       style   of   bracket   used  in  the  document  just  by  changing  the
       bracket-label command.  Another is that sorting and  merging  of  cita‐
       tions will not necessarily be inhibited if the flags are used.

       If  a label is to be inserted into the text, it will be attached to the
       line preceding the .[ line.  If there is no such line,  then  an  extra
       line will be inserted before the .[ line and a warning will be given.

       There  is  no special notation for making a citation to multiple refer‐
       ences.  Just use a sequence  of  citations,  one  for  each  reference.
       Don’t put anything between the citations.  The labels for all the cita‐
       tions  will  be attached to the line preceding the first citation.  The
       labels may also be sorted or merged.  See the description of the <> la‐
       bel    expression,    and    of    the     sort-adjacent-labels     and
       abbreviate-label-ranges  commands.   A  label will not be merged if its
       citation has a non‐empty opening‐text or  closing‐text.   However,  the
       labels for a citation using the ] flag and without any closing‐text im‐
       mediately followed by a citation using the [ flag and without any open‐
       ing‐text  may  be  sorted  and  merged even though the first citation’s
       opening‐text or the second citation’s closing‐text is  non‐empty.   (If
       you wish to prevent this, use the dummy character escape sequence \& as
       the first citation’s closing‐text.)

   Commands
       Commands are contained between lines starting with .R1 and .R2.  Recog‐
       nition  of  these  lines can be prevented by the -R option.  When a .R1
       line is recognized any accumulated references are flushed out.  Neither
       .R1 nor .R2 lines, nor anything between them, is output.

       Commands are separated by newlines or semicolons.  A  number  sign  (#)
       introduces  a comment that extends to the end of the line, but does not
       conceal the newline.  Each command is broken up into words.  Words  are
       separated  by spaces or tabs.  A word that begins with a (neutral) dou‐
       ble quote (") extends to the next double quote that is not followed  by
       another  double  quote.  If there is no such double quote, the word ex‐
       tends to the end of the line.  Pairs of double quotes in a word  begin‐
       ning  with a double quote collapse to one double quote.  Neither a num‐
       ber sign nor a semicolon is recognized inside double  quotes.   A  line
       can  be  continued by ending it with a backslash “\”; this works every‐
       where except after a number sign.

       Each command name that is marked with * has an associated negative com‐
       mand no-name that undoes the effect of name.  For example, the  no-sort
       command  specifies  that references should not be sorted.  The negative
       commands take no arguments.

       In the following description each argument must be a single word; field
       is used for a single upper or lower case letter naming a field;  fields
       is used for a sequence of such letters; m and n are used for a non‐neg‐
       ative numbers; string is used for an arbitrary string; file is used for
       the name of a file.

       abbreviate* fields string1 string2 string3 string4
              Abbreviate the first names of fields.  An initial letter will be
              separated  from another initial letter by string1, from the last
              name by string2, and from anything else (such as “von” or  “de”)
              by  string3.  These default to a period followed by a space.  In
              a hyphenated first name, the initial of the first  part  of  the
              name will be separated from the hyphen by string4; this defaults
              to  a period.  No attempt is made to handle any ambiguities that
              might result from abbreviation.  Names  are  abbreviated  before
              sorting and before label construction.

       abbreviate-label-ranges* string
              Three  or  more adjacent labels that refer to consecutive refer‐
              ences will be abbreviated to a label consisting of the first la‐
              bel, followed by string, followed by the last  label.   This  is
              mainly useful with numeric labels.  If string is omitted, it de‐
              faults to “-”.

       accumulate*
              Accumulate  references  instead of writing out each reference as
              it is encountered.  Accumulated references will be  written  out
              whenever a reference of the form
                     .[
                     $LIST$
                     .]
              is  encountered,  after all input files have been processed, and
              whenever a .R1 line is recognized.

       annotate* field string
              field is an annotation; print it at the end of the reference  as
              a paragraph preceded by the line

                     .string

              If  string  is  omitted, it will default to AP; if field is also
              omitted it will default to X.  Only one field can be an  annota‐
              tion.

       articles string ...
              Each  string  is a definite or indefinite article, and should be
              ignored at the beginning of T fields when  sorting.   Initially,
              “a”, “an”, and “the” are recognized as articles.

       bibliography file ...
              Write  out  all  the  references contained in each bibliographic
              database file.  This command should  come  last  in  an  .R1/.R2
              block.

       bracket-label string1 string2 string3
              In  the  text,  bracket each label with string1 and string2.  An
              occurrence of string2 immediately followed by  string1  will  be
              turned into string3.  The default behavior is as follows.
                     bracket-label \*([. \*(.] ", "

       capitalize fields
              Convert fields to caps and small caps.

       compatible*
              Recognize  .R1  and  .R2 even when followed by a character other
              than space or newline.

       database file ...
              Search each bibliographic database file.  For each file,  if  an
              index  file.i  created  by  indxbib(1)  exists,  then it will be
              searched instead; each index can cover multiple databases.

       date-as-label* string
              string is a label expression that specifies a string with  which
              to  replace  the D field after constructing the label.  See sub‐
              section “Label expressions” below for a description of label ex‐
              pressions.  This command is useful if you do not  want  explicit
              labels  in  the  reference  list, but instead want to handle any
              necessary disambiguation by qualifying the  date  in  some  way.
              The  label  used in the text would typically be some combination
              of the author and date.  In most cases you should also  use  the
              no-label-in-reference command.  For example,
                     date-as-label D.+yD.y%a*D.-y
              would  attach  a disambiguating letter to the year part of the D
              field in the reference.

       default-database*
              The default database should be searched.  This  is  the  default
              behavior,  so  the negative version of this command is more use‐
              ful.  refer determines whether the default  database  should  be
              searched  on  the  first  occasion that it needs to do a search.
              Thus a no-default-database command must be given before then, in
              order to be effective.

       discard* fields
              When the reference is  read,  fields  should  be  discarded;  no
              string definitions for fields will be output.  Initially, fields
              are XYZ.

       et-al* string m n
              Control  use of et al. in the evaluation of @ expressions in la‐
              bel expressions.  If the number of authors needed  to  make  the
              author sequence unambiguous is u and the total number of authors
              is  t  then the last t-u authors will be replaced by string pro‐
              vided that t-u is not less than m and t is not less than n.  The
              default behavior is as follows.
                     et-al " et al" 2 3
              Note the absence of a dot from  the  end  of  the  abbreviation,
              which is arguably not correct.  (Et al[.]  is short for et alli,
              as etc. is short for et cetera.)

       include file
              Include file and interpret the contents as commands.

       join-authors string1 string2 string3
              Join multiple authors together with strings.  When there are ex‐
              actly two authors, they will be joined with string1.  When there
              are  more  than two authors, all but the last two will be joined
              with string2, and the last  two  authors  will  be  joined  with
              string3.   If string3 is omitted, it will default to string1; if
              string2 is also omitted it will also default  to  string1.   For
              example,
                     join-authors " and " ", " ", and "
              will restore the default method for joining authors.

       label-in-reference*
              When  outputting  the  reference, define the string [F to be the
              reference’s label.  This is the default behavior, so  the  nega‐
              tive version of this command is more useful.

       label-in-text*
              For  each  reference output a label in the text.  The label will
              be separated from the  surrounding  text  as  described  in  the
              bracket-label  command.   This  is  the default behavior, so the
              negative version of this command is more useful.

       label string
              string is a label expression describing how to label each refer‐
              ence.

       separate-label-second-parts string
              When merging two‐part labels, separate the second  part  of  the
              second label from the first label with string.  See the descrip‐
              tion of the <> label expression.

       move-punctuation*
              In  the  text,  move any punctuation at the end of line past the
              label.  It is usually a good idea to give  this  command  unless
              you are using superscripted numbers as labels.

       reverse* string
              Reverse  the  fields whose names are in string.  Each field name
              can be followed by a number which  says  how  many  such  fields
              should be reversed.  If no number is given for a field, all such
              fields will be reversed.

       search-ignore* fields
              While searching for keys in databases for which no index exists,
              ignore  the  contents  of fields.  Initially, fields XYZ are ig‐
              nored.

       search-truncate* n
              Only require the first n characters of keys to be given.  In ef‐
              fect when searching for a given key words in  the  database  are
              truncated  to  the maximum of n and the length of the key.  Ini‐
              tially, n is 6.

       short-label* string
              string is a label expression that specifies an alternative (usu‐
              ally shorter) style of label.  This is used when the #  flag  is
              given in the citation.  When using author‐date style labels, the
              identity  of  the  author or authors is sometimes clear from the
              context, and so it may be desirable to omit the  author  or  au‐
              thors from the label.  The short-label command will typically be
              used  to  specify  a label containing just a date and possibly a
              disambiguating letter.

       sort* string
              Sort references according to string.  References will  automati‐
              cally  be  accumulated.  string should be a list of field names,
              each followed by a number, indicating how many fields  with  the
              name  should  be  used for sorting.  “+” can be used to indicate
              that all the fields with the name should be used.  Also . can be
              used to indicate the references should be sorted using the (ten‐
              tative) label.  (Subsection “Label expressions” below  describes
              the concept of a tentative label.)

       sort-adjacent-labels*
              Sort labels that are adjacent in the text according to their po‐
              sition  in  the  reference list.  This command should usually be
              given if the abbreviate-label-ranges command has been given,  or
              if  the  label  expression  contains a <> expression.  This will
              have no effect unless references are being accumulated.

   Label expressions
       Label expressions can be evaluated both normally and tentatively.   The
       result  of  normal evaluation is used for output.  The result of tenta‐
       tive evaluation, called the tentative label, is used to gather the  in‐
       formation  that normal evaluation needs to disambiguate the label.  La‐
       bel expressions specified by the date-as-label and short-label commands
       are not evaluated tentatively.  Normal and tentative evaluation are the
       same for all types of expression other than @, *,  and  %  expressions.
       The description below applies to normal evaluation, except where other‐
       wise specified.

       field
       field n
              The n‐th part of field.  If n is omitted, it defaults to 1.

       'string'
              The characters in string literally.

       @      All the authors joined as specified by the join-authors command.
              The  whole  of each author’s name will be used.  However, if the
              references are sorted by author (that is, the sort specification
              starts with “A+”), then authors’ last names  will  be  used  in‐
              stead, provided that this does not introduce ambiguity, and also
              an initial subsequence of the authors may be used instead of all
              the authors, again provided that this does not introduce ambigu‐
              ity.   The use of only the last name for the i‐th author of some
              reference is considered to be ambiguous if there is  some  other
              reference, such that the first i-1 authors of the references are
              the  same,  the  i‐th authors are not the same, but the i‐th au‐
              thors last names are the same.  A proper initial subsequence  of
              the  sequence  of authors for some reference is considered to be
              ambiguous if there is a reference with some  other  sequence  of
              authors which also has that subsequence as a proper initial sub‐
              sequence.   When  an initial subsequence of authors is used, the
              remaining authors are replaced by the string  specified  by  the
              et-al command; this command may also specify additional require‐
              ments  that  must  be  met  before an initial subsequence can be
              used.  @ tentatively evaluates to a canonical representation  of
              the  authors, such that authors that compare equally for sorting
              purpose will have the same representation.

       %n
       %a
       %A
       %i
       %I     The serial number of the reference formatted  according  to  the
              character  following  the  %.   The serial number of a reference
              is 1 plus the number of earlier references with  same  tentative
              label as this reference.  These expressions tentatively evaluate
              to an empty string.

       expr*  If  there  is another reference with the same tentative label as
              this reference, then expr, otherwise an empty string.  It tenta‐
              tively evaluates to an empty string.

       expr+n
       expr-n The first (+) or last (-) n upper or lower case letters or  dig‐
              its  of expr.  roff special characters (such as \('a) count as a
              single letter.  Accent strings are retained but do not count to‐
              wards the total.

       expr.l expr converted to lowercase.

       expr.u expr converted to uppercase.

       expr.c expr converted to caps and small caps.

       expr.r expr reversed so that the last name is first.

       expr.a expr with first names  abbreviated.   Fields  specified  in  the
              abbreviate  command are abbreviated before any labels are evalu‐
              ated.  Thus .a is useful only when you want a field to be abbre‐
              viated in a label but not in a reference.

       expr.y The year part of expr.

       expr.+y
              The part of expr before the year, or the whole  of  expr  if  it
              does not contain a year.

       expr.-y
              The part of expr after the year, or an empty string if expr does
              not contain a year.

       expr.n The last name part of expr.

       expr1~expr2
              expr1  except  that  if the last character of expr1 is - then it
              will be replaced by expr2.

       expr1 expr2
              The concatenation of expr1 and expr2.

       expr1|expr2
              If expr1 is non‐empty then expr1 otherwise expr2.

       expr1&expr2
              If expr1 is non‐empty then expr2 otherwise an empty string.

       expr1?expr2:expr3
              If expr1 is non‐empty then expr2 otherwise expr3.

       <expr> The label is in two parts, which are separated by expr.  Two ad‐
              jacent two‐part labels which have the same first  part  will  be
              merged by appending the second part of the second label onto the
              first   label   separated   by   the  string  specified  in  the
              separate-label-second-parts command (initially, a comma followed
              by a space); the resulting label will also be a  two‐part  label
              with  the  same  first part as before merging, and so additional
              labels can be merged into it.  It is permissible for  the  first
              part  to be empty; this may be desirable for expressions used in
              the short-label command.

       (expr) The same as expr.  Used for grouping.

       The above expressions  are  listed  in  order  of  precedence  (highest
       first); & and | have the same precedence.

   Macro interface
       Each  reference starts with a call to the macro ]-.  The string [F will
       be  defined  to  be  the  label  for   this   reference,   unless   the
       no-label-in-reference command has been given.  There then follows a se‐
       ries  of  string definitions, one for each field: string [X corresponds
       to field X.  The register [P is set to 1 if  the  P  field  contains  a
       range  of pages.  The [T, [A and [O registers are set to 1 according as
       the T, A and O fields end with any of .?! (an  end‐of‐sentence  charac‐
       ter).   The [E register will be set to 1 if the [E string contains more
       than one name.  The reference is followed by a call to  the  ][  macro.
       The  first  argument to this macro gives a number representing the type
       of the reference.  If a reference contains a J field, it will be  clas‐
       sified  as  type  1,  otherwise  if  it  contains a B field, it will be
       type 3, otherwise if it contains a G or R field it will be type 4, oth‐
       erwise if it contains an I field it will be type 2, otherwise  it  will
       be type 0.  The second argument is a symbolic name for the type: other,
       journal-article, book, article-in-book, or tech-report.  Groups of ref‐
       erences  that have been accumulated or are produced by the bibliography
       command are preceded by a call to the ]< macro and followed by  a  call
       to the ]> macro.

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -R     Don’t recognize lines beginning with .R1/.R2.

       Other options are equivalent to refer commands.

       -a n            reverse An

       -b              no-label-in-text; no-label-in-reference

       -B              See below.

       -c fields       capitalize fields

       -C              compatible

       -e              accumulate

       -f n            label %n

       -i fields       search-ignore fields

       -k              label L~%a

       -k field        label field~%a

       -l              label A.nD.y%a

       -l m            label A.n+mD.y%a

       -l ,n           label A.nD.y-n%a

       -l m,n          label A.n+mD.y-n%a

       -n              no-default-database

       -p db‐file      database db‐file

       -P              move-punctuation

       -s spec         sort spec

       -S              label "(A.n|Q) ', ' (D.y|D)"; bracket‐label " (" ) "; "

       -t n            search-truncate n

       The B option has command equivalents with the addition  that  the  file
       names specified on the command line are processed as if they were argu‐
       ments to the bibliography command instead of in the normal way.

       -B              annotate X AP; no-label-in-reference

       -B field.macro  annotate field macro; no-label-in-reference

Environment
       REFER  If set, overrides the default database.

Files
       /usr/dict/papers/Ind
              Default database.

       file.i Index files.

       /usr/share/groff/1.23.0/tmac/refer.tmac
              defines  macros  and strings facilitating integration with macro
              packages that wish to support refer.

       refer uses temporary files.  See the groff(1) man page for  details  of
       where such files are created.

Bugs
       In  label  expressions, <> expressions are ignored inside .char expres‐
       sions.

Examples
       We can illustrate the operation of refer with  a  sample  bibliographic
       database  containing  one entry and a simple roff document to cite that
       entry.

              $ cat > my-db-file
              %A Daniel P.\& Friedman
              %A Matthias Felleisen
              %C Cambridge, Massachusetts
              %D 1996
              %I The MIT Press
              %T The Little Schemer, Fourth Edition
              $ refer ‐p my-db-file
              Read the book
              .[
              friedman
              .]
              on your summer vacation.
              <Control+D>
              .lf 1 -
              Read the book\*([.1\*(.]
              .ds [F 1
              .]-
              .ds [A Daniel P. Friedman and Matthias Felleisen
              .ds [C Cambridge, Massachusetts
              .ds [D 1996
              .ds [I The MIT Press
              .ds [T The Little Schemer, Fourth Edition
              .nr [T 0
              .nr [A 0
              .][ 2 book
              .lf 5 -
              on your summer vacation.

       The foregoing shows us that refer (a) produces a label “1”; (b)  brack‐
       ets  that label with interpolations of the “[.”  and “.]”  strings; (c)
       calls a macro “]-”; (d) defines strings and  registers  containing  the
       label and bibliographic data for the reference; (e) calls a macro “][”;
       and (f) uses the lf request to restore the line numbers of the original
       input.  As discussed in subsection “Macro interface” above, it is up to
       the  document  or a macro package to employ and format this information
       usefully.  Let us see how we might turn groff_ms(7) to this task.

              $ REFER=my-db-file groff -R -ms
              .LP
              Read the book
              .[
              friedman
              .]
              on your summer vacation.
              Commentary is available.\*{*\*}
              .FS \*{*\*}
              Space reserved for penetrating insight.
              .FE

       ms’s automatic footnote numbering mechanism is not aware of refer’s la‐
       bel numbering, so we have manually specified a (superscripted) symbolic
       footnote for our non‐bibliographic aside.

See also
       “Some Applications of Inverted Indexes on the Unix System”,  by  M.  E.
       Lesk,  1978,  AT&T Bell Laboratories Computing Science Technical Report
       No. 69.

       indxbib(1), lookbib(1), lkbib(1)

groff 1.23.0                      2 July 2023                         refer(1)
───────────────────────────────────────────────────────────────────────────────
soelim(1)                   General Commands Manual                  soelim(1)

Name
       soelim - recursively interpolate source requests in roff or other  text
       files

Synopsis
       soelim [-Crt] [-I dir] [input‐file ...]

       soelim --help

       soelim -v
       soelim --version

Description
       GNU  soelim is a preprocessor for the groff(7) document formatting sys‐
       tem.  soelim works as a filter to eliminate source requests in  roff(7)
       input files; that is, it replaces lines of the form “.so included‐file”
       within  each text input‐file with the contents of included‐file, recur‐
       sively.  By default, it writes lf requests as well to record  the  name
       and line number of each input‐file and included‐file, so that any diag‐
       nostics  produced  by  later processing can be accurately traced to the
       original input.  Options allow this information to be  suppressed  (-r)
       or supplied in TeX comments instead (-t).  In the absence of input‐file
       arguments,  soelim  reads the standard input stream.  Output is written
       to the standard output stream.

       If the name of a macro‐file contains a backslash, use \\ or \e to embed
       it.  To embed a space, write “\ ” (backslash followed by a space).  Any
       other escape sequence in macro‐file, including “\[rs]”, prevents soelim
       from replacing the source request.

       The dot must be at the beginning of a line and must be followed by “so”
       without intervening spaces or tabs for soelim to handle it.  This  con‐
       vention  allows  source  requests  to be “protected” from processing by
       soelim, for instance as part of macro definitions or “if” requests.

       There must also be at least one space between “so” and  its  macro‐file
       argument.  The -C option overrides this requirement.

       The  foregoing  is the limit of soelim’s understanding of the roff lan‐
       guage; it does not, for example, replace the input line
              .if 1 .so otherfile
       with the contents of otherfile.  With its -r option, therefore,  soelim
       can  be used to process text files in general, to flatten a tree of in‐
       put documents.

       soelim was designed to handle situations where the  target  of  a  roff
       source   request  requires  a  preprocessor  such  as  eqn(1),  pic(1),
       refer(1), or tbl(1).  The usual processing sequence of groff(1)  is  as
       follows.

                 input        sourced
                 file          file
                   ⎪             ⎪
                   ↓             ↓
               preprocessor ⎯→ troff ⎯→ postprocessor
                                             ⎪
                                             ↓
                                          output
                                           file

       That  is, files sourced with “so” are normally read only by the format‐
       ter, troff.  soelim is not required for troff to source files.

       If a file to be sourced should also be preprocessed, it must already be
       read before the input file passes through  the  preprocessor.   soelim,
       normally invoked via groff’s -s option, handles this.

                 input
                 file
                   ⎪
                   ↓
                 soelim ⎯→ preprocessor ⎯→ troff ⎯→ postprocessor
                   ↑                                     ⎪
                   ⎪                                     ↓
                sourced                               output
                 file                                  file

Options
       --help  displays  a  usage message, while -v and --version show version
       information; all exit afterward.

       -C     Recognize an input line starting with .so even  if  a  character
              other than a space or newline follows.

       -I dir Search the directory dir path for input‐ and included‐files.  -I
              may  be  specified  more  than once; each dir is searched in the
              given order.  To search the  current  working  directory  before
              others,  add  “-I  .”  at  the  desired  place;  it is otherwise
              searched last.

       -r     Write files “raw”; do not add lf requests.

       -t     Emit TeX comment lines starting with “%” indicating the  current
              file  and line number, rather than lf requests for the same pur‐
              pose.

       If both -r and -t are given, the last one specified controls.

See also
       groff(1)

groff 1.23.0                      2 July 2023                        soelim(1)
───────────────────────────────────────────────────────────────────────────────
tbl(1)                      General Commands Manual                     tbl(1)

Name
       tbl - prepare tables for groff documents

Synopsis
       tbl [-C] [file ...]

       tbl --help

       tbl -v
       tbl --version

Description
       The GNU implementation of tbl is part of the groff(1) document  format‐
       ting  system.   tbl is a troff(1) preprocessor that translates descrip‐
       tions of tables embedded in roff(7) input files into the  language  un‐
       derstood by troff.  It copies the contents of each file to the standard
       output stream, except that lines between .TS and .TE are interpreted as
       table  descriptions.  While GNU tbl’s input syntax is highly compatible
       with AT&T tbl, the output GNU tbl produces cannot be processed by  AT&T
       troff;  GNU troff (or a troff implementing any GNU extensions employed)
       must be used.  Normally, tbl is not executed directly by the user,  but
       invoked  by  specifying the -t option to groff(1).  If no file operands
       are given on the command line, or if file is “-”, tbl reads  the  stan‐
       dard input stream.

   Overview
       tbl  expects  to find table descriptions between input lines that begin
       with .TS (table start) and .TE (table end).  Each such table region en‐
       closes one or more table descriptions.  Within a  table  region,  table
       descriptions  beyond  the  first must each be preceded by an input line
       beginning with .T&.  This mechanism does not start a new table  region;
       all  table descriptions are treated as part of their .TS/.TE enclosure,
       even if they are boxed or have column headings that  repeat  on  subse‐
       quent pages (see below).

       (Experienced  roff users should observe that tbl is not a roff language
       interpreter: the default control character must be used, and no  spaces
       or tabs are permitted between the control character and the macro name.
       These  tbl  input  tokens remain as‐is in the output, where they become
       ordinary macro calls.  Macro packages  often  define  TS,  T&,  and  TE
       macros  to  handle issues of table placement on the page.  tbl produces
       groff code to define these macros as empty if their definitions do  not
       exist when the formatter encounters a table region.)

       Each  table  region may begin with region options, and must contain one
       or more table definitions; each  table  definition  contains  a  format
       specification  followed  by  one or more input lines (rows) of entries.
       These entries comprise the table data.

   Region options
       The line immediately following the .TS token  may  specify  region  op‐
       tions,  keywords  that influence the interpretation or rendering of the
       region as a whole or all  table  entries  within  it  indiscriminately.
       They  must be separated by commas, spaces, or tabs.  Those that require
       a parenthesized argument permit spaces and tabs  between  the  option’s
       name and the opening parenthesis.  Options accumulate and cannot be un‐
       set  within a region once declared; if an option that takes a parameter
       is repeated, the last occurrence controls.  If present, the set of  re‐
       gion options must be terminated with a semicolon (;).

       Any  of  the  allbox, box, doublebox, frame, and doubleframe region op‐
       tions makes a table “boxed” for the purpose of later discussion.

       allbox Enclose each table entry in a box; implies box.

       box    Enclose the entire table region in a box.  As a  GNU  extension,
              the alternative option name frame is also recognized.

       center Center  the table region with respect to the current indentation
              and line length; the default is to left‐align it.  As a GNU  ex‐
              tension, the alternative option name centre is also recognized.

       decimalpoint(c)
              Recognize  character c as the decimal separator in columns using
              the N (numeric) classifier (see subsection “Column  classifiers”
              below).  This is a GNU extension.

       delim(xy)
              Recognize  characters  x  and y as start and end delimiters, re‐
              spectively, for eqn(1) input, and ignore input between them.   x
              and y need not be distinct.

       doublebox
              Enclose  the  entire  table region in a double box; implies box.
              As a GNU extension, the alternative option name  doubleframe  is
              also recognized.

       expand Spread  the table horizontally to fill the available space (line
              length minus indentation) by increasing column separation.   Or‐
              dinarily,  a table is made only as wide as necessary to accommo‐
              date the widths  of  its  entries  and  its  column  separations
              (whether  specified or default).  When expand applies to a table
              that exceeds the available horizontal space,  column  separation
              is  reduced  as  far  as necessary (even to zero).  tbl produces
              groff input that issues a diagnostic if such compression occurs.
              The column modifier x (see below) overrides this option.

       linesize(n)
              Draw lines or  rules  (e.g.,  from  box)  with  a  thickness  of
              n  points.  The default is the current type size when the region
              begins.  This option is ignored on terminal devices.

       nokeep Don’t use roff diversions to manage page breaks.  Normally,  tbl
              employs  them to avoid breaking a page within a table row.  This
              usage can sometimes interact badly with macro packages’ own  use
              of  diversions—when  footnotes, for example, are employed.  This
              is a GNU extension.

       nospaces
              Ignore leading and trailing spaces in table entries.  This is  a
              GNU extension.

       nowarn Suppress  diagnostic  messages  produced  at document formatting
              time when the line or page lengths are inadequate to  contain  a
              table row.  This is a GNU extension.

       tab(c) Use  the  character  c instead of a tab to separate entries in a
              row of table data.

   Table format specification
       The table format specification is mandatory: it determines  the  number
       of columns in the table and directs how the entries within it are to be
       typeset.   The  format specification is a series of column descriptors.
       Each descriptor encodes a classifier followed by  zero  or  more  modi‐
       fiers.   Classifiers  are  letters  (recognized  case‐insensitively) or
       punctuation symbols; modifiers consist of or begin with letters or  nu‐
       merals.  Spaces, tabs, newlines, and commas separate descriptors.  New‐
       lines and commas are special; they apply the descriptors following them
       to  a subsequent row of the table.  (This enables column headings to be
       centered or emboldened while the table entries for the  data  are  not,
       for instance.)  We term the resulting group of column descriptors a row
       definition.   Within  a  row  definition, separation between column de‐
       scriptors (by spaces or tabs) is often optional; only  some  modifiers,
       described below, make separation necessary.

       Each  column descriptor begins with a mandatory classifier, a character
       that selects from one of several arrangements.  Some determine the  po‐
       sitioning  of  table entries within a rectangular cell: centered, left‐
       aligned, numeric (aligned to a configurable decimal separator), and  so
       on.   Others  perform special operations like drawing lines or spanning
       entries from adjacent cells in the table.  Except for “|”, any  classi‐
       fier  can be followed by one or more modifiers; some of these accept an
       argument, which in GNU tbl  can  be  parenthesized.   Modifiers  select
       fonts, set the type size, and perform other tasks described below.

       The format specification can occupy multiple input lines, but must con‐
       clude with a dot “.” followed by a newline.  Each row definition is ap‐
       plied  in turn to one row of the table.  The last row definition is ap‐
       plied to rows of table data in excess of the row definitions.

       For clarity in this document’s examples, we shall write classifiers  in
       uppercase  and  modifiers  in  lowercase.  Thus, “CbCb,LR.” defines two
       rows of two columns.  The first row’s entries are  centered  and  bold‐
       faced;  the  second  and any further rows’ first and second columns are
       left‐ and right‐aligned, respectively.

       The row definition with the most column descriptors determines the num‐
       ber of columns in the table; any row definition with fewer  is  implic‐
       itly  extended  on the right‐hand side with L classifiers as many times
       as necessary to make the table rectangular.

   Column classifiers
       The L, R, and C classifiers are the easiest to understand and use.

       A, a   Center longest entry in this column,  left‐align  remaining  en‐
              tries in the column with respect to the centered entry, then in‐
              dent  all  entries  by one en.  Such “alphabetic” entries (hence
              the name of the classifier) can be used in the same column as L‐
              classified entries, as in “LL,AR.”.  The  A  entries  are  often
              termed “sub‐columns” due to their indentation.

       C, c   Center entry within the column.

       L, l   Left‐align entry within the column.

       N, n   Numerically  align  entry  in the column.  tbl aligns columns of
              numbers vertically at the units place.  If multiple decimal sep‐
              arators are adjacent to a digit, it uses the rightmost  one  for
              vertical  alignment.   If  there  is  no  decimal separator, the
              rightmost digit is used for vertical alignment;  otherwise,  tbl
              centers  the  entry within the column.  The roff dummy character
              \& in an entry marks the glyph preceding  it  (if  any)  as  the
              units  place; if multiple instances occur in the data, the left‐
              most is used for alignment.

              If N‐classified entries share a column with L or R entries,  tbl
              centers the widest N entry with respect to the widest L or R en‐
              try,  preserving the alignment of N entries with respect to each
              other.

              The appearance of eqn equations within N‐classified columns  can
              be  troublesome  due to the foregoing textual scan for a decimal
              separator.  Use the delim region option to make tbl  ignore  the
              data within eqn delimiters for that purpose.

       R, r   Right‐align entry within the column.

       S, s   Span previous entry on the left into this column.

       ^      Span  entry  in  the same column from the previous row into this
              row.

       _, -   Replace table entry with a horizontal rule.  An empty table  en‐
              try  is  expected  to correspond to this classifier; if data are
              found there, tbl issues a diagnostic message.

       =      Replace table entry with a double horizontal rule.  An empty ta‐
              ble entry is expected to correspond to this classifier; if  data
              are found there, tbl issues a diagnostic message.

       |      Place a vertical rule (line) on the corresponding row of the ta‐
              ble  (if  two  of  these  are adjacent, a double vertical rule).
              This classifier does not contribute to the column count  and  no
              table  entries  correspond  to it.  A | to the left of the first
              column descriptor or to the right of the  last  one  produces  a
              vertical rule at the edge of the table; these are redundant (and
              ignored) in boxed tables.

       To  change  the  table format within a tbl region, use the .T& token at
       the start of a line.  It is followed by a format specification and  ta‐
       ble data, but not region options.  The quantity of columns in a new ta‐
       ble format thus introduced cannot increase relative to the previous ta‐
       ble  format;  in that case, you must end the table region and start an‐
       other.  If that will not serve because the region uses box  options  or
       the columns align in an undesirable manner, you must design the initial
       table  format  specification to include the maximum quantity of columns
       required, and use the S horizontal spanning classifier where  necessary
       to achieve the desired columnar alignment.

       Attempting  to horizontally span in the first column or vertically span
       on the first row is an error.  Non‐rectangular span areas are also  not
       supported.

   Column modifiers
       Any  number  of modifiers can follow a column classifier.  Arguments to
       modifiers, where accepted, are case‐sensitive.  If the same modifier is
       applied to a column specifier more than once, or if  conflicting  modi‐
       fiers are applied, only the last occurrence has effect.  The modifier x
       is  mutually  exclusive  with  e and w, but e is not mutually exclusive
       with w; if these are used in combination, x unsets both e and w,  while
       either e or w overrides x.

       b, B   Typeset entry in boldface, abbreviating f(B).

       d, D   Align  a  vertically spanned table entry to the bottom (“down”),
              instead of the center, of its range.  This is a GNU extension.

       e, E   Equalize the widths of columns with this modifier.   The  column
              with the largest width controls.  This modifier sets the default
              line length used in a text block.

       f, F   Select  the typeface for the table entry.  This modifier must be
              followed by a font or style name  (one  or  two  characters  not
              starting with a digit), font mounting position (a single digit),
              or  a  name  or  mounting position of any length in parentheses.
              The last form is a GNU extension.  (The parameter corresponds to
              that accepted by the troff ft request.)  A  one‐character  argu‐
              ment  not in parentheses must be separated by one or more spaces
              or tabs from what follows.

       i, I   Typeset entry in an oblique or italic face, abbreviating f(I).

       m, M   Call a groff macro before typesetting a text block (see  subsec‐
              tion “Text blocks” below).  This is a GNU extension.  This modi‐
              fier  must  be followed by a macro name of one or two characters
              or a name of any length in parentheses.  A  one‐character  macro
              name  not in parentheses must be separated by one or more spaces
              or tabs from what follows.  The named macro must be defined  be‐
              fore the table region containing this column modifier is encoun‐
              tered.   The  macro should contain only simple groff requests to
              change text formatting, like  adjustment  or  hyphenation.   The
              macro  is  called  after  the column modifiers b, f, i, p, and v
              take effect; it can thus override other column modifiers.

       p, P   Set the type size for the table entry.  This  modifier  must  be
              followed  by an integer n with an optional leading sign.  If un‐
              signed, the type size is set to n scaled points.  Otherwise, the
              type size is incremented or decremented per the sign by n scaled
              points.  The use of a signed multi‐digit number is a GNU  exten‐
              sion.   (The parameter corresponds to that accepted by the troff
              ps request.)  If a type size modifier is followed  by  a  column
              separation  modifier  (see  below), they must be separated by at
              least one space or tab.

       t, T   Align a vertically spanned table entry to the  top,  instead  of
              the center, of its range.

       u, U   Move  the  column up one half‐line, “staggering” the rows.  This
              is a GNU extension.

       v, V   Set the vertical spacing to be used in a text block.  This modi‐
              fier must be followed by an integer n with an  optional  leading
              sign.   If  unsigned,  the  vertical spacing is set to n points.
              Otherwise, the vertical spacing is  incremented  or  decremented
              per  the sign by n points.  The use of a signed multi‐digit num‐
              ber is a GNU extension.  (This parameter corresponds to that ac‐
              cepted by the troff vs request.)  If a vertical spacing modifier
              is followed by a column separation modifier  (see  below),  they
              must be separated by at least one space or tab.

       w, W   Set  the column’s minimum width.  This modifier must be followed
              by a number, which is either a unitless integer, or a roff hori‐
              zontal measurement in parentheses.  Parentheses are required  if
              the  width  is  to be followed immediately by an explicit column
              separation (alternatively, follow the width  with  one  or  more
              spaces  or  tabs).   If  no  unit is specified, ens are assumed.
              This modifier sets the default line length used in a text block.

       x, X   Expand the column.  After computing the column widths,  distrib‐
              ute  any  remaining  line length evenly over all columns bearing
              this modifier.  Applying the x modifier to more than one  column
              is  a GNU extension.  This modifier sets the default line length
              used in a text block.

       z, Z   Ignore the table entries corresponding to this column for  width
              calculation  purposes; that is, compute the column’s width using
              only the information in its descriptor.

       n      A numeric suffix on a column descriptor sets the separation dis‐
              tance (in ens) from the succeeding column; the  default  separa‐
              tion is 3n.  This separation is proportionally multiplied if the
              expand  region  option is in effect; in the case of tables wider
              than the output line length, this separation might be  zero.   A
              negative  separation  cannot  be specified.  A separation amount
              after the last column in a row is nonsensical and provokes a di‐
              agnostic from tbl.

   Table data
       The table data come after the format specification.   Each  input  line
       corresponds  to  a  table  row, except that a backslash at the end of a
       line of table data continues an entry on the next  input  line.   (Text
       blocks,  discussed below, also spread table entries across multiple in‐
       put lines.)  Table entries within a row are separated in the input by a
       tab character by default; see the tab region option above.  Excess  en‐
       tries  in  a row of table data (those that have no corresponding column
       descriptor, not even an implicit one arising from rectangularization of
       the table) are discarded with a diagnostic message.  roff control lines
       are accepted between rows of table data and within text blocks.  If you
       wish to visibly mark an empty table entry in the document source, popu‐
       late it with the \& roff dummy character.  The table  data  are  inter‐
       rupted  by  a line consisting of the .T& input token, and conclude with
       the line .TE.

       Ordinarily, a table entry is typeset rigidly.  It is not  filled,  bro‐
       ken,  hyphenated, adjusted, or populated with additional inter‐sentence
       space.  tbl instructs the formatter to measure each table entry  as  it
       occurs  in  the input, updating the width required by its corresponding
       column.  If the z modifier applies to the column, this  measurement  is
       ignored;  if w applies and its argument is larger than this width, that
       argument is used instead.   In  contrast  to  conventional  roff  input
       (within a paragraph, say), changes to text formatting, such as font se‐
       lection or vertical spacing, do not persist between entries.

       Several forms of table entry are interpreted specially.

       • If a table row contains only an underscore or equals sign (_ or =), a
         single  or  double  horizontal  rule  (line),  respectively, is drawn
         across the table at that point.

       • A table entry containing only _ or = on an otherwise populated row is
         replaced by a single or double horizontal rule, respectively, joining
         its neighbors.

       • Prefixing a lone underscore or equals sign with a backslash also  has
         meaning.   If a table entry consists only of \_ or \= on an otherwise
         populated row, it is replaced by a single or double horizontal  rule,
         respectively, that does not (quite) join its neighbors.

       • A table entry consisting of \Rx, where x is any roff ordinary or spe‐
         cial character, is replaced by enough repetitions of the glyph corre‐
         sponding  to  x to fill the column, albeit without joining its neigh‐
         bors.

       • On any row but the first, a table entry of \^ causes the entry  above
         it to span down into the current one.

       On  occasion,  these  special  tokens  may be required as literal table
       data.  To use either _ or = literally and alone in an entry, prefix  or
       suffix  it with the roff dummy character \&.  To express \_, \=, or \R,
       use a roff escape sequence to interpolate the backslash (\e or  \[rs]).
       A reliable way to emplace the \^ glyph sequence within a table entry is
       to use a pair of groff special character escape sequences (\[rs]\[ha]).

       Rows  of  table  entries  can  be interleaved with groff control lines;
       these do not count as table data.  On such lines  the  default  control
       character  (.)  must  be  used  (and not changed); the no‐break control
       character is not recognized.  To start the first table entry in  a  row
       with a dot, precede it with the roff dummy character \&.

   Text blocks
       An ordinary table entry’s contents can make a column, and therefore the
       table,  excessively wide; the table then exceeds the line length of the
       page, and becomes ugly or is exposed to truncation by  the  output  de‐
       vice.   When  a  table  entry  requires  more conventional typesetting,
       breaking across more than one output line (and thereby  increasing  the
       height of its row), it can be placed within a text block.

       tbl interprets a table entry beginning with “T{” at the end of an input
       line  not  as  table data, but as a token starting a text block.  Simi‐
       larly, “T}” at the start of an input line ends a text  block;  it  must
       also  end  the  table entry.  Text block tokens can share an input line
       with other table data (preceding T{ and following T}).  Input lines be‐
       tween these tokens are formatted in a diversion by troff.  Text  blocks
       cannot be nested.  Multiple text blocks can occur in a table row.

       Text  blocks are formatted as was the text prior to the table, modified
       by applicable column descriptors.  Specifically, the classifiers A,  C,
       L,  N, R, and S determine a text block’s alignment within its cell, but
       not its adjustment.  Add na or ad requests to the beginning of  a  text
       block  to  alter its adjustment distinctly from other text in the docu‐
       ment.  As with other table entries, when a text block ends, any  alter‐
       ations to formatting parameters are discarded.  They do not affect sub‐
       sequent table entries, not even other text blocks.

       If w or x modifiers are not specified for all columns of a text block’s
       span,  the  default  length of the text block (more precisely, the line
       length used to  process  the  text  block  diversion)  is  computed  as
       L×C/(N+1),  where L is the current line length, C the number of columns
       spanned by the text block, and N the number of columns  in  the  table.
       If necessary, you can also control a text block’s width by including an
       ll  (line length) request in it prior to any text to be formatted.  Be‐
       cause a diversion is used to format the  text  block,  its  height  and
       width  are  subsequently  available in the registers dn and dl, respec‐
       tively.

   roff interface
       The register TW stores the width of the table region in basic units; it
       can’t be used within the region itself, but is defined before  the  .TE
       token  is output so that a groff macro named TE can make use of it.  T.
       is a Boolean‐valued register indicating whether the bottom of the table
       is being processed.  The #T register marks the top of the table.  Avoid
       using these names for any other purpose.

       tbl also defines a macro T# to produce the bottom and side lines  of  a
       boxed  table.   While  tbl  itself arranges for the output to include a
       call of this macro at the end of such a table, it can also be  used  by
       macro packages to create boxes for multi‐page tables by calling it from
       a  page  footer  macro that is itself called by a trap planted near the
       bottom of the page.  See section “Limitations” below for more on multi‐
       page tables.

       GNU tbl internally employs register, string, macro, and diversion names
       beginning with the numeral 3.  A document to be preprocessed  with  GNU
       tbl should not use any such identifiers.

   Interaction with eqn
       tbl  should  always  be  called before eqn(1).  (groff(1) automatically
       arranges preprocessors in the correct order.)  Don’t call the EQ and EN
       macros within tables; instead, set up delimiters in your eqn input  and
       use the delim region option so that tbl will recognize them.

   GNU tbl enhancements
       In  addition to extensions noted above, GNU tbl removes constraints en‐
       dured by users of AT&T tbl.

       • Region options can be specified in any lettercase.

       • There is no limit on the number of columns in a table, regardless  of
         their classification, nor any limit on the number of text blocks.

       • All  table  rows are considered when deciding column widths, not just
         those occurring in the first 200 input lines of a region.  Similarly,
         table continuation (.T&) tokens are  recognized  outside  a  region’s
         first 200 input lines.

       • Numeric and alphabetic entries may appear in the same column.

       • Numeric and alphabetic entries may span horizontally.

   Using GNU tbl within macros
       You can embed a table region inside a macro definition.  However, since
       tbl writes its own macro definitions at the beginning of each table re‐
       gion, it is necessary to call end macros instead of ending macro defin‐
       itions with “..”.  Additionally, the escape character must be disabled.

       Not all tbl features can be exercised from such macros because tbl is a
       roff  preprocessor: it sees the input earlier than troff does.  For ex‐
       ample, vertically aligning decimal separators fails if the numbers con‐
       taining them occur as macro or string parameters; the alignment is per‐
       formed by tbl itself, which sees only \$1, \$2, and so on,  and  there‐
       fore  can’t  recognize a decimal separator that only appears later when
       troff interpolates a macro or string definition.

       Using tbl macros within conditional input (that is, contingent upon  an
       if,  ie, el, or while request) can result in misleading line numbers in
       subsequent diagnostics.  tbl unconditionally injects  its  output  into
       the  source  document, but the conditional branch containing it may not
       be taken, and if it is not, the lf requests that tbl injects to restore
       the source line number cannot take effect.  Consider copying the  input
       line  counter register c. and restoring its value at a convenient loca‐
       tion after applicable arithmetic.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -C     Enable  AT&T compatibility mode: recognize .TS and .TE even when
              followed by a character other than space or  newline.   Further‐
              more, interpret the uninterpreted leader escape sequence \a.

Limitations
       Multi‐page  tables,  if  boxed and/or if you want their column headings
       repeated after page breaks, require support at the time the document is
       formatted.  A convention for such support has arisen in macro  packages
       such  as  ms, mm, and me.  To use it, follow the .TS token with a space
       and then “H”; this will be interpreted by the formatter as a  TS  macro
       call  with  an  H  argument.   Then, within the table data, call the TH
       macro; this informs the macro package where the headings end.  If  your
       table  has no such heading rows, or you do not desire their repetition,
       call TH immediately after the table format specification.  If a  multi‐
       page table is boxed or has repeating column headings, do not enclose it
       with  keep/release macros, or divert it in any other way.  Further, the
       bp request will not cause a page break in a “TS  H”  table.   Define  a
       macro  to wrap bp: invoke it normally if there is no current diversion.
       Otherwise, pass the macro call to the  enclosing  diversion  using  the
       transparent  line  escape  sequence  \!; this will “bubble up” the page
       break to the output device.  See section “Examples” below for a  demon‐
       stration.

       Double  horizontal  rules  are not supported by grotty(1); single rules
       are used instead.  grotty also ignores half‐line motions, so the u col‐
       umn modifier has no effect.  On terminal devices (“nroff mode”),  hori‐
       zontal rules and box borders occupy a full vee of space; this amount is
       doubled for doublebox tables.  Tables using these features thus require
       more vertical space in nroff mode than in troff mode: write ne requests
       accordingly.  Vertical rules between columns are drawn in the space be‐
       tween  columns in nroff mode; using double vertical rules and/or reduc‐
       ing the column separation below the default can make them ugly or over‐
       strike them with table data.

       A text block within a table must be able to fit on one page.

       Using \a to put leaders in table entries does not work in GNU tbl,  ex‐
       cept  in  compatibility mode.  This is correct behavior: \a is an unin‐
       terpreted leader.  You can still use the roff  leader  character  (Con‐
       trol+A)  or  define a string to use \a as it was designed: to be inter‐
       preted only in copy mode.

              .ds a \a
              .TS
              box center tab(;);
              Lw(2i)0 L.
              Population\*a;6,327,119
              .TE

                         ┌───────────────────────────────┐
                         │ Population..........6,327,119 │
                         └───────────────────────────────┘

       A leading  and/or  trailing  |  in  a  format  specification,  such  as
       “|LCR|.”,  produces an en space between the vertical rules and the con‐
       tent of the adjacent columns.  If no such space is desired (so that the
       rule abuts the content), you can introduce “dummy”  columns  with  zero
       separation and empty corresponding table entries before and/or after.

              .TS
              center tab(#);
              R0|L C R0|L.
              _
              #levulose#glucose#dextrose#
              _
              .TE

       These dummy columns have zero width and are therefore invisible; unfor‐
       tunately they usually don’t work as intended on terminal devices.

Examples
       It  can  be easier to acquire the language of tbl through examples than
       formal description, especially at first.

              .TS
              box center tab(#);
              Cb Cb
              L L.
              Ability#Application
              Strength#crushes a tomato
              Dexterity#dodges a thrown tomato
              Constitution#eats a month‐old tomato without becoming ill
              Intelligence#knows that a tomato is a fruit
              Wisdom#chooses \f[I]not\f[] to put tomato in a fruit salad
              Charisma#sells obligate carnivores tomato‐based fruit salads
              .TE

       ┌────────────────────────────────────────────────────────────────────┐
       │   Ability                          Application                     │
       │ Strength       crushes a tomato                                    │
       │ Dexterity      dodges a thrown tomato                              │
       │ Constitution   eats a month‐old tomato without becoming ill        │
       │ Intelligence   knows that a tomato is a fruit                      │
       │ Wisdom         chooses not to put tomato in a fruit salad          │
       │ Charisma       sells obligate carnivores tomato‐based fruit salads │
       └────────────────────────────────────────────────────────────────────┘

       The A and N column classifiers can be easier to grasp in visual render‐
       ing than in description.

              .TS
              center tab(;);
              CbS,LN,AN.
              Daily energy intake (in MJ)
              Macronutrients
              .\" assume 3 significant figures of precision
              Carbohydrates;4.5
              Fats;2.25
              Protein;3
              .T&
              LN,AN.
              Mineral
              Pu-239;14.6
              _
              .T&
              LN.
              Total;\[ti]24.4
              .TE

                                Daily energy intake (in MJ)
                                Macronutrients
                                  Carbohydrates       4.5
                                  Fats                2.25
                                  Protein             3
                                Mineral
                                  Pu‐239             14.6
                                ────────────────────────────
                                Total               ~24.4

       Next, we’ll lightly adapt a compact presentation of spanning,  vertical
       alignment,  and  zero‐width  column modifiers from the mandoc reference
       for its tbl interpreter.  It rewards close study.

              .TS
              box center tab(:);
              Lz  S | Rt
              Ld| Cb| ^
              ^ | Rz  S.
              left:r
              l:center:
              :right
              .TE

                                    ┌────────────┬───┐
                                    │ le│ft       │ r │
                                    │   │ center │   │
                                    │ l │      right │
                                    └───┴────────────┘

       Row staggering is not visually achievable on terminal  devices,  but  a
       table using it can remain comprehensible nonetheless.

              .TS
              center tab(|);
              Cf(BI) Cf(BI) Cf(B), C C Cu.
              n|n\f[B]\[tmu]\f[]n|difference
              1|1
              2|4|3
              3|9|5
              4|16|7
              5|25|9
              6|36|11
              .TE

                                    n   n×n   difference
                                    1    1
                                    2    4        3
                                    3    9        5
                                    4   16        7
                                    5   25        9
                                    6   36        11

       Some tbl features cannot be illustrated in the limited environment of a
       portable man page.

       We  can  define  a  macro outside of a tbl region that we can call from
       within it to cause a page break inside a multi‐page boxed  table.   You
       can  choose  a  different  name;  be sure to change both occurrences of
       “BP”.

              .de BP
              .  ie '\\n(.z'' .bp \\$1
              .  el \!.BP \\$1
              ..

See also
       “Tbl—A Program to Format Tables”, by M. E. Lesk, 1976 (revised 16 Janu‐
       ary 1979), AT&T Bell Laboratories Computing  Science  Technical  Report
       No. 49.

       The spanning example above was taken from mandoc’s man page for its tbl
       implementation ⟨https://man.openbsd.org/tbl.7⟩.

       groff(1), troff(1)

groff 1.23.0                      2 July 2023                           tbl(1)
───────────────────────────────────────────────────────────────────────────────
tfmtodit(1)                 General Commands Manual                tfmtodit(1)

Name
       tfmtodit - adapt TeX Font Metrics files for use with groff and grodvi

Synopsis
       tfmtodit [-s] [-g gf‐file] [-k skew‐char] tfm‐file map‐file font‐
                description

       tfmtodit --help

       tfmtodit -v
       tfmtodit --version

Description
       tfmtodit  creates  a  font description file for use with groff(1)’s dvi
       output device.  tfm‐file is the name of the TeX font  metric  file  for
       the font.  map‐file assigns groff ordinary or special character identi‐
       fiers  to glyph indices in the font; it should consist of a sequence of
       lines of the form
              i c1 ... cn
       where i is a position of the glyph in  the  font  in  decimal,  and  c1
       through  cn  are  glyph  identifiers in the form used by groff font de‐
       scriptions.  If a glyph has no groff names but exists in  tfm‐file,  it
       is  put in the groff font description file as an unnamed glyph.  Output
       is written in groff_font(5) format to font‐description,  a  file  named
       for the intended groff font name.

       If  the font is “special”, meaning that groff should search it whenever
       a glyph is not found in the current font, use the -s  option  and  name
       font‐description  in  the  fonts  directive in the output device’s DESC
       file.

       To do a good job of math typesetting, groff requires font metric infor‐
       mation not present in tfm‐file.  This is because TeX has separate  math
       italic fonts, whereas groff uses normal italic fonts for math.  The ad‐
       ditional information required by groff is given by the two arguments to
       the  math_fit  macro  in  the Metafont programs for the Computer Modern
       fonts.  In a text font (a font for which math_fit is  false),  Metafont
       normally ignores these two arguments.  Metafont can be made to put this
       information  into  the GF (“generic font”) files it produces by loading
       the following definition after cmbase when creating cm.base.
              def ignore_math_fit(expr left_adjustment,right_adjustment) =
                  special "adjustment";
                  numspecial left_adjustment*16/designsize;
                  numspecial right_adjustment*16/designsize;
                  enddef;
       For the EC font family, load the  following  definition  after  exbase;
       consider patching exbase.mf locally.
              def ignore_math_fit(expr left_adjustment,right_adjustment) =
                  ori_special "adjustment";
                  ori_numspecial left_adjustment*16/designsize;
                  ori_numspecial right_adjustment*16/designsize;
                  enddef;
       The  only  difference from the previous example is the “ori_” prefix to
       “special” and “numspecial”.  The GF file created  using  this  modified
       cm.base  or  exbase.mf  should  be  specified with the -g option, which
       should not be given for a font for which math_fit is true.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -g gf‐file
              Use  the  gf‐file  produced by Metafont containing “special” and
              “numspecial” commands to obtain additional font metric  informa‐
              tion.

       -k skew‐char
              The skew character of this font is at position skew‐char.  skew‐
              char  should  be  an integer; it may be given in decimal, with a
              leading 0 in octal, or with a leading 0x  in  hexadecimal.   Any
              kerns whose second component is skew‐char are ignored.

       -s     Add the special directive to the font description file.

Files
       /usr/share/groff/1.23.0/font/devdvi/DESC
              describes the dvi output device.

       /usr/share/groff/1.23.0/font/devdvi/F
              describes the font known as F on device dvi.

       /usr/share/groff/1.23.0/font/devdvi/generate/ec.map
       /usr/share/groff/1.23.0/font/devdvi/generate/msam.map
       /usr/share/groff/1.23.0/font/devdvi/generate/msbm.map
       /usr/share/groff/1.23.0/font/devdvi/generate/tc.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texb.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texex.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texi.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texitt.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texmi.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texr.map
       /usr/share/groff/1.23.0/font/devdvi/generate/texsy.map
       /usr/share/groff/1.23.0/font/devdvi/generate/textex.map
       /usr/share/groff/1.23.0/font/devdvi/generate/textt.map
              map  glyph  indices  in  TeX fonts to groff ordinary and special
              character identifiers.  ec.map is used  for  TREC,  TIEC,  TBEC,
              TBIEC,  HREC,  HIEC,  HBEC, HBIEC, CWEC, and CWIEC; msam.map for
              SA; msbm.map for SB; tc.map for TRTC, TITC, TBTC,  TBITC,  HRTC,
              HITC, HBTC, HBITC, CWTC, and CWITC; texb.map for TB, HR, HI, HB,
              and  HBI;  texex.map for EX; texi.map for TI and TBI; texitt.map
              for CWI; texmi.map for MI; texr.map for  TR;  texsy.map  for  S;
              textex.map for SC; and textt.map for CW.

See also
       groff(1), grodvi(1), groff_font(5)

groff 1.23.0                      2 July 2023                      tfmtodit(1)
───────────────────────────────────────────────────────────────────────────────
troff(1)                    General Commands Manual                   troff(1)

Name
       troff - GNU roff typesetter and document formatter

Synopsis
       troff [-abcCEiRUz] [-d ctext] [-d string=text] [-f font‐family]
             [-F font‐directory] [-I inclusion‐directory] [-m macro‐package]
             [-M macro‐directory] [-n page‐number] [-o page‐list]
             [-r cnumeric‐expression] [-r register=numeric‐expression]
             [-T output‐device] [-w warning‐category] [-W warning‐category]
             [file ...]

       troff --help

       troff -v
       troff --version

Description
       GNU  troff  transforms groff(7) language input into the device‐indepen‐
       dent output format described in groff_out(5); troff is thus  the  heart
       of  the  GNU  roff document formatting system.  If no file operands are
       given on the command line, or if file is “-”, the standard input stream
       is read.

       GNU troff is functionally compatible with the AT&T troff typesetter and
       features numerous extensions.  Many people prefer to use  the  groff(1)
       command,  a  front end which also runs preprocessors and output drivers
       in the appropriate order and with appropriate options.

Options
       -h and --help display a usage message, while -v and --version show ver‐
       sion information; all exit afterward.

       -a     Generate a plain text approximation of the typeset output.   The
              read‐only  register .A is set to 1.  This option produces a sort
              of abstract preview of the formatted output.

              • Page breaks are marked by a phrase in angle brackets; for  ex‐
                ample, “<beginning of page>”.

              • Lines are broken where they would be in the formatted output.

              • A  horizontal  motion of any size is represented as one space.
                Adjacent horizontal motions are not combined.   Inter‐sentence
                space nodes (those arising from the second argument to the .ss
                request) are not represented.

              • Vertical motions are not represented.

              • Special  characters  are rendered in angle brackets; for exam‐
                ple, the default soft hyphen character appears as “<hy>”.

              The above description should not be considered a  specification;
              the details of -a output are subject to change.

       -b     Write a backtrace reporting the state of troff’s input parser to
              the  standard  error  stream  with each diagnostic message.  The
              line numbers given in the backtrace might not always be correct,
              because troff’s idea of line numbers can be confused by requests
              that append to macros.

       -c     Start with color output disabled.

       -C     Enable  AT&T  troff  compatibility  mode;   implies   -c.    See
              groff_diff(7).

       -d ctext
       -d string=text
              Define  roff  string c or string as text.  c must be one charac‐
              ter; string can be of arbitrary length.  Such string assignments
              happen before any macro file is loaded,  including  the  startup
              file.   Due  to  getopt_long(3)  limitations,  c  cannot be, and
              string cannot contain, an equals sign, even  though  that  is  a
              valid character in a roff identifier.

       -E     Inhibit troff error messages; implies -Ww.  This option does not
              suppress messages sent to the standard error stream by documents
              or macro packages using tm or related requests.

       -f fam Use fam as the default font family.

       -F dir Search  in directory dir for the selected output device’s direc‐
              tory of device and font description files.  See the  description
              of  GROFF_FONT_PATH  in  section “Environment” below for the de‐
              fault search locations and ordering.

       -i     Read the standard input stream after all named input files  have
              been processed.

       -I dir Search  the  directory dir for files (those named on the command
              line; in psbb, so, and soquiet  requests;  and  in  “\X'ps:  im‐
              port'”, “\X'ps: file'”, and “\X'pdf: pdfpic'” device control es‐
              cape  sequences).   -I may be specified more than once; each dir
              is searched in the given order.  To search the  current  working
              directory  before others, add “-I .” at the desired place; it is
              otherwise searched last.  -I works similarly to,  and  is  named
              for, the “include” option of Unix C compilers.

       -m name
              Process  the  file  name.tmac  prior to any input files.  If not
              found, tmac.name is attempted.  name (in both  arrangements)  is
              presumed   to   be   a   macro  file;  see  the  description  of
              GROFF_TMAC_PATH in section “Environment” below for  the  default
              search locations and ordering.

       -M dir Search  directory  dir  for macro files.  See the description of
              GROFF_TMAC_PATH in section “Environment” below for  the  default
              search locations and ordering.

       -n num Begin numbering pages at num.  The default is 1.

       -o list
              Output  only  pages  in list, which is a comma‐separated list of
              inclusive page ranges; n means page n, m-n means every page  be‐
              tween  m  and n, -n means every page up to n, and n- means every
              page from n on.  troff stops processing and exits after  format‐
              ting the last page enumerated in list.

       -r cnumeric‐expression
       -r register=numeric‐expression
              Define  roff  register  c  or  register  as  numeric‐expression.
              c must be a one‐character name; register  can  be  of  arbitrary
              length.   Such register assignments happen before any macro file
              is loaded, including the startup file.   Due  to  getopt_long(3)
              limitations, c cannot be, and register cannot contain, an equals
              sign,  even  though  that is a valid character in a roff identi‐
              fier.

       -R     Don’t load troffrc and troffrc-end.

       -T dev Prepare output for device dev.  The default is ps; see groff(1).

       -U     Operate in unsafe mode, enabling the open, opena, pi,  pso,  and
              sy requests, which are disabled by default because they allow an
              untrusted  input  document  to write to arbitrary file names and
              run arbitrary commands.  This option also adds the  current  di‐
              rectory  to the macro package search path; see the -m and -M op‐
              tions above.

       -w name
       -W name
              Enable (-w) or inhibit (-W) warnings in category name.  See sec‐
              tion “Warnings” below.

       -z     Suppress formatted output.

Warnings
       Warning diagnostics emitted by troff are divided into  named,  numbered
       categories.   The name associated with each warning category is used by
       the -w and -W options.  Each category is also assigned a power of  two;
       the  sum  of enabled category codes is used by the warn request and the
       .warn register.  Warnings of each category are produced under the  fol‐
       lowing circumstances.

              ┌───────────────────────┬─────────────────────────────┐
              │ Bit   Code   Category │ Bit    Code      Category   │
              ├───────────────────────┼─────────────────────────────┤
              │   0      1   char     │  10      1024   reg         │
              │   1      2   number   │  11      2048   tab         │
              │   2      4   break    │  12      4096   right-brace │
              │   3      8   delim    │  13      8192   missing     │
              │   4     16   el       │  14     16384   input       │
              │   5     32   scale    │  15     32768   escape      │
              │   6     64   range    │  16     65536   space       │
              │   7    128   syntax   │  17    131072   font        │
              │   8    256   di       │  18    262144   ig          │
              │   9    512   mac      │  19    524288   color       │
              │                       │  20   1048576   file        │
              └───────────────────────┴─────────────────────────────┘

       break           4   A  filled output line could not be broken such that
                           its length was less than  the  output  line  length
                           \n[.l].  This category is enabled by default.

       char            1   No  mounted  font defines a glyph for the requested
                           character.  This category is enabled by default.

       color      524288   An undefined color name was  selected,  an  attempt
                           was  made  to  define a color using an unrecognized
                           color space, an invalid component in a color defin‐
                           ition was encountered, or an attempt  was  made  to
                           redefine a default color.

       delim           8   The  closing  delimiter  in  an escape sequence was
                           missing or mismatched.

       di            256   A di, da, box, or boxa request was invoked  without
                           an argument when there was no current diversion.

       el             16   The el request was encountered with no prior corre‐
                           sponding ie request.

       escape      32768   An unsupported escape sequence was encountered.

       file      1048576   An  attempt  was  made to load a file that does not
                           exist.  This category is enabled by default.

       font       131072   A non‐existent font was selected, or the  selection
                           was  ignored  because  a  font selection escape se‐
                           quence was used after the output line  continuation
                           escape sequence on an input line.  This category is
                           enabled by default.

       ig         262144   An  invalid  escape  sequence occurred in input ig‐
                           nored using the ig request.  This warning  category
                           diagnoses  a condition that is an error when it oc‐
                           curs in non‐ignored input.

       input       16384   An invalid character occurred on the input stream.

       mac           512   An undefined string, macro, or diversion was  used.
                           When  such  an object is dereferenced, an empty one
                           of that name is automatically created.  So,  unless
                           it  is  later deleted, at most one warning is given
                           for each.

                           This warning is also emitted  upon  an  attempt  to
                           move  an  unplanted trap macro.  In such cases, the
                           unplanted macro is not dereferenced, so it  is  not
                           created if it does not exist.

       missing      8192   A request was invoked with a mandatory argument ab‐
                           sent.

       number          2   An  invalid  numeric  expression  was  encountered.
                           This category is enabled by default.

       range          64   A numeric expression was out of range for its  con‐
                           text.

       reg          1024   An  undefined register was used.  When an undefined
                           register is dereferenced, it is  automatically  de‐
                           fined  with  a  value of 0.  So, unless it is later
                           deleted, at most one warning is given for each.

       right-brace  4096   A right brace escape sequence  \}  was  encountered
                           where a number was expected.

       scale          32   A  scaling  unit  inappropriate  to its context was
                           used in a numeric expression.

       space       65536   A space was missing between a request or macro  and
                           its argument.  This warning is produced when an un‐
                           defined  name longer than two characters is encoun‐
                           tered and the first two characters of the name con‐
                           stitute a defined name.  No request is invoked,  no
                           macro  called,  and  an empty macro is not defined.
                           This category is enabled by default.  It never  oc‐
                           curs in compatibility mode.

       syntax        128   A   self‐contradictory  hyphenation  mode  was  re‐
                           quested; an empty or incomplete numeric  expression
                           was  encountered;  an operand to a numeric operator
                           was missing; an attempt was made to define a recur‐
                           sive, empty, or nonsensical character class;  or  a
                           groff extension conditional expression operator was
                           used while in compatibility mode.

       tab          2048   A  tab character was encountered where a number was
                           expected, or appeared in an  unquoted  macro  argu‐
                           ment.

       Two warning names group other warning categories for convenience.

       all    All  warning categories except di, mac, and reg.  This shorthand
              is intended to produce all warnings that are useful  with  macro
              packages  and  documents  written for AT&T troff and its descen‐
              dants, which have less fastidious diagnostics than GNU troff.

       w      All warning categories.  Authors of documents and macro packages
              targeting groff are encouraged to use this setting.

Environment
       GROFF_FONT_PATH and GROFF_TMAC_PATH each accept a search path of direc‐
       tories; that is, a list of directory names separated  by  the  system’s
       path component separator character.  On Unix systems, this character is
       a colon (:); on Windows systems, it is a semicolon (;).

       GROFF_FONT_PATH
              A  list  of directories in which to seek the selected output de‐
              vice’s directory of device and font  description  files.   troff
              will scan directories given as arguments to any specified -F op‐
              tions  before  these,  then  in a site‐specific directory (/usr/
              share/groff/site-font), a standard  location  (/usr/share/groff/
              1.23.0/font),  and a compatibility directory (/usr/lib/font) af‐
              ter them.

       GROFF_TMAC_PATH
              A list of directories in which to search for macro files.  troff
              will scan directories given as arguments to any specified -M op‐
              tions before these, then the current directory (only if  in  un‐
              safe mode), the user’s home directory, a site‐specific directory
              (/usr/share/groff/site-tmac),  and  a  standard  location (/usr/
              share/groff/1.23.0/tmac) after them.

       GROFF_TYPESETTER
              Set the default output device.  If empty or not set, ps is used.
              The -T option overrides GROFF_TYPESETTER.

       SOURCE_DATE_EPOCH
              A timestamp (expressed as seconds since the Unix epoch)  to  use
              as  the  output creation timestamp in place of the current time.
              The time is converted to human‐readable form using  localtime(3)
              when  the  formatter starts up and stored in registers usable by
              documents and macro packages.

       TZ     The timezone to use when converting the current time  (or  value
              of SOURCE_DATE_EPOCH) to human‐readable form; see tzset(3).

Files
       /usr/share/groff/1.23.0/tmac/troffrc
              is an initialization macro file loaded before any macro packages
              specified with -m options.

       /usr/share/groff/1.23.0/tmac/troffrc-end
              is  an initialization macro file loaded after all macro packages
              specified with -m options.

       /usr/share/groff/1.23.0/tmac/name.tmac
              are macro files distributed with groff.

       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

       /usr/share/groff/1.23.0/font/devname/F
              describes the font F of device name.

       troffrc and troffrc-end are sought neither in the current nor the  home
       directory  by  default  for  security reasons, even if the -U option is
       specified.  Use the -M command‐line option or the GROFF_TMAC_PATH envi‐
       ronment variable to add these directories to the search path if  neces‐
       sary.

Authors
       The GNU version of troff was originally written by James Clark; he also
       wrote  the  original  version  of  this  document, which was updated by
       Werner Lemberg ⟨wl@gnu.org⟩,  Bernd  Warken  ⟨groff-bernd.warken-72@web
       .de⟩, and G. Branden Robinson ⟨g.branden.robinson@gmail.com⟩.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       groff(1)
              offers  an  overview  of  the  GNU roff system and describes its
              front end executable.

       groff(7)
              details the groff language, including a short but complete  ref‐
              erence  of  all  predefined  requests, registers, and escape se‐
              quences.

       groff_char(7)
              explains the syntax of groff special character escape sequences,
              and lists all special characters predefined by the language.

       groff_diff(7)
              enumerates the differences between AT&T device‐independent troff
              and groff.

       groff_font(5)
              covers the format of groff device and font description files.

       groff_out(5)
              describes the format of troff’s output.

       groff_tmac(5)
              includes information about macro files that ship with groff.

       roff(7)
              supplies background on roff systems in general, including point‐
              ers to further related documentation.

groff 1.23.0                      2 July 2023                         troff(1)
───────────────────────────────────────────────────────────────────────────────
xtotroff(1)                 General Commands Manual                xtotroff(1)

Name
       xtotroff - convert X font metrics into groff font metrics

Synopsis
       xtotroff [-d destination‐directory] [-r resolution] [-s type‐size]
                font‐map

       xtotroff --help

       xtotroff -v
       xtotroff --version

Description
       xtotroff uses font‐map to create groff(1) font description  files  from
       X11  fonts.   Each  line  in  font‐map consists of a series of lines of
       paired groff font names and X font names as X Logical Font  Description
       (XLFD) patterns, with the pair members separated by spaces and/or tabs.
       For example, an input font‐map file consisting of the line
              TB -adobe-times-bold-r-normal--*-*-*-*-p-*-iso8859-1
       maps  the  XLFD  on the right to the groff font name TB, conventionally
       “Times bold”.

       xtotroff opens a connection to the running X server to query  its  font
       catalog,  and  aborts if it cannot.  If necessary, the wildcards in the
       XLFD patterns are populated with the arguments to the  -r  and  -s  op‐
       tions.   If  a font name is still ambiguous, xtotroff aborts.  For each
       successful mapping, xtotroff creates a groff font description  file  in
       the  current  working  directory  (or  that specified by the ‐d option)
       named for each groff font, and reports the mapping to the standard out‐
       put stream.

Options
       --help displays a usage message, while -v and  --version  show  version
       information; all exit afterward.

       -d destination‐directory
              Write font descriptions to destination‐directory rather than the
              current working directory.

       -r resolution
              Set the resolution for all font patterns in font‐map.  The value
              is  used for both the horizontal and vertical motion quanta.  If
              not specified, a resolution of 75dpi is assumed.

       -s type‐size
              Set the type size in points for all font patterns  in  font‐map.
              If not specified, a size of 10 points is assumed.

Files
       /usr/share/groff/1.23.0/font/FontMap-X11
              is  the font mapping file used to produce the pre‐generated font
              description files, supplied with groff, of X11 core fonts corre‐
              sponding to the 13 base Type 1 fonts for PostScript level 1.

Bugs
       The  only  supported  font  encodings  are  “iso8859-1”   and   “adobe-
       fontspecific”.

See also
       “X  Logical  Font Description Conventions” ⟨https://www.x.org/releases/
       X11R7.6/doc/xorg-docs/specs/XLFD/xlfd.html⟩, by Jim Flowers and Stephen
       Gildea.

       X(7), groff(1), gxditview(1), troff(1), groff_font(5)

groff 1.23.0                      2 July 2023                      xtotroff(1)
───────────────────────────────────────────────────────────────────────────────
groff_font(5)                 File Formats Manual                groff_font(5)

Name
       groff_font - GNU roff device and font description files

Description
       The groff font and output device description formats are slight  exten‐
       sions  of  those used by AT&T device‐independent troff.  In distinction
       to the AT&T implementation, groff lacks a binary format; all files  are
       text  files.  (Plan 9 troff has also abandoned the binary format.)  The
       device and font description files for a device name are stored in a de‐
       vname directory.  The device description file is called DESC, and,  for
       each font supported by the device, a font description file is called f,
       where  f is usually an abbreviation of a font’s name and/or style.  For
       example, the ps (PostScript) device has groff  font  description  files
       for Times roman (TR) and Zapf Chancery Medium italic (ZCMI), among many
       others,  while  the  utf8 device (for terminal emulators) has only font
       descriptions for the roman, italic, bold, and bold‐italic styles (R, I,
       B, and BI, respectively).

       Device and font description files are read by the formatter, troff, and
       by output drivers.  The programs typically delegate these  files’  pro‐
       cessing to an internal library, libgroff, ensuring their consistent in‐
       terpretation.

DESC file format
       The  DESC  file  contains  a  series of directives; each begins a line.
       Their order is not important, with two exceptions: (1) the  res  direc‐
       tive  must  precede any papersize directive; and (2) the charset direc‐
       tive must come last (if at all).  If  a  directive  name  is  repeated,
       later entries in the file override previous ones (except that the paper
       dimensions  are  computed  based  on  the  res directive last seen when
       papersize is encountered).  Spaces and/or tabs separate words  and  are
       ignored  at line boundaries.  Comments start with the “#” character and
       extend to the end of a line.  Empty lines are ignored.

       family fam
              The default font family is fam.

       fonts n F1 ... Fn
              Fonts F1, ..., Fn are mounted at font positions  m+1,  ...,  m+n
              where m is the number of styles (see below).  This directive may
              extend over more than one line.  A font name of 0 causes no font
              to be mounted at the corresponding position.

       hor n  The  horizontal  motion  quantum  is  n basic units.  Horizontal
              quantities are rounded to multiples of n.

       image_generator program
              Use program to generate PNG images from PostScript input.  Under
              GNU/Linux, this is usually gs(1), but under other  systems  (no‐
              tably  Cygwin)  it might be set to another name.  The grohtml(1)
              driver uses this directive.

       paperlength n
              The vertical dimension of the output medium  is  n  basic  units
              (deprecated: use papersize instead).

       papersize format‐or‐dimension‐pair‐or‐file‐name ...
              The  dimensions of the output medium are as according to the ar‐
              gument, which is either a standard paper format, a pair  of  di‐
              mensions,  or the name of a plain text file containing either of
              the foregoing.  Recognized paper formats are  the  ISO  and  DIN
              formats A0–A7, B0–B7, C0–C7, and D0–D7; the U.S. formats letter,
              legal,  tabloid, ledger, statement, and executive; and the enve‐
              lope formats com10, monarch,  and  DL.   Matching  is  performed
              without regard for lettercase.

              Alternatively,  the  argument  can  be  a  custom  paper  format
              length,width (with no spaces before or after the  comma).   Both
              length  and width must have a unit appended; valid units are “i”
              for inches, “c” for centimeters, “p” for points, and “P” for pi‐
              cas.  Example: “12c,235p”.  An argument that starts with a digit
              is always treated as a custom paper format.

              Finally, the argument can be a file name (e.g., /etc/papersize);
              if the file can be opened, the first line is read  and  a  match
              attempted  against  each  other form.  No comment syntax is sup‐
              ported.

              More than one argument can be specified; each is scanned in turn
              and the first valid paper specification used.

       paperwidth n
              The horizontal dimension of the output medium is n  basic  units
              (deprecated: use papersize instead).

       pass_filenames
              Direct  troff  to  emit  the  name  of  the  source  file  being
              processed.  This is achieved with the intermediate  output  com‐
              mand “x F”, which grohtml interprets.

       postpro program
              Use program as the postprocessor.

       prepro program
              Use  program  as  a preprocessor.  The html and xhtml output de‐
              vices use this directive.

       print program
              Use program as the print spooler.  If omitted, groff’s -l and -L
              options are ignored.

       res n  The device resolution is n basic units per inch.

       sizes s1 ... sn 0
              The device has fonts at s1, ..., sn scaled points  (see  below).
              The  list  of sizes must be terminated by a 0.  Each si can also
              be a range of sizes m–n.  The list can extend over more than one
              line.

       sizescale n
              A typographical point is subdivided into n scaled  points.   The
              default is 1.

       styles S1 ... Sm
              The  first  m font mounting positions are associated with styles
              S1, ..., Sm.

       tcommand
              The postprocessor can handle the t  and  u  intermediate  output
              commands.

       unicode
              The  output  device  supports  the  complete Unicode repertoire.
              This directive is useful only for devices which produce  charac‐
              ter entities instead of glyphs.

              If  unicode  is  present,  no charset section is required in the
              font description files since the  Unicode  handling  built  into
              groff is used.  However, if there are entries in a font descrip‐
              tion  file’s  charset  section, they either override the default
              mappings for those particular characters  or  add  new  mappings
              (normally for composite characters).

              The utf8, html, and xhtml output devices use this directive.

       unitwidth n
              Quantities  in the font description files are in basic units for
              fonts whose type size is n scaled points.

       unscaled_charwidths
              Make the font  handling  module  always  return  unscaled  glyph
              widths.  The grohtml driver uses this directive.

       use_charnames_in_special
              troff should encode named glyphs inside device control commands.
              The grohtml driver uses this directive.

       vert n The  vertical motion quantum is n basic units.  Vertical quanti‐
              ties are rounded to multiples of n.

       charset
              This directive and the rest of the file are ignored.  It is rec‐
              ognized for compatibility with other troff implementations.   In
              GNU  troff,  character set repertoire is described on a per‐font
              basis.

       troff  recognizes  but  ignores  the  directives  spare1,  spare2,  and
       biggestfont.

       The  res,  unitwidth, fonts, and sizes lines are mandatory.  Directives
       not listed above are ignored by troff but may be used by postprocessors
       to obtain further information about the device.

Font description file format
       On typesetting output devices, each font is typically available at mul‐
       tiple sizes.  While paper measurements in the device  description  file
       are in absolute units, measurements applicable to fonts must be propor‐
       tional  to  the type size.  groff achieves this using the precedent set
       by AT&T device‐independent troff: one font size is chosen  as  a  norm,
       and  all  others are scaled linearly relative to that basis.  The “unit
       width” is the number of basic units per point when the font is rendered
       at this nominal size.

       For instance, groff’s lbp device uses a unitwidth of  800.   Its  Times
       roman  font  (“TR”)  has a spacewidth of 833; this is also the width of
       its comma, period, centered period, and  mathematical  asterisk,  while
       its  “M” is 2,963 basic units.  Thus, an “M” on the lbp device is 2,963
       basic units wide at a notional type size  of  800  points.   (800‐point
       type is not practical for most purposes, but using it enables the quan‐
       tities in the font description files to be expressed as integers.)

       A  font  description file has two sections.  The first is a sequence of
       directives, and is parsed similarly to the DESC file  described  above.
       Except for the directive names that begin the second section, their or‐
       dering  is immaterial.  Later directives of the same name override ear‐
       lier ones, spaces and tabs are handled in the same way,  and  the  same
       comment syntax is supported.  Empty lines are ignored throughout.

       name F The  name  of  the  font  is F.  “DESC” is an invalid font name.
              Simple integers are valid, but their use is discouraged.  (groff
              requests and escape sequences interpret non‐negative font  names
              as mounting positions instead.  Further, a font named “0” cannot
              be automatically mounted by the fonts directive of a DESC file.)

       spacewidth n
              The width of an unadjusted inter‐word space is n basic units.

       The  directives above must appear in the first section; those below are
       optional.

       slant n
              The font’s glyphs have a slant of n degrees; a positive n slants
              in the direction of text flow.

       ligatures lig1 ... lign [0]
              Glyphs lig1, ..., lign are ligatures; possible ligatures are ff,
              fi, fl, ffi, and ffl.  For compatibility with other troff imple‐
              mentations, the list of ligatures may be terminated  with  a  0.
              The list of ligatures must not extend over more than one line.

       special
              The  font  is  special:  when  a  glyph is requested that is not
              present in the current font, it is sought in any  mounted  fonts
              that bear this property.

       Other  directives in this section are ignored by troff, but may be used
       by postprocessors to obtain further information about the font.

       The second section contains one or two subsections.  These  can  appear
       in  either  order;  the first one encountered commences the second sec‐
       tion.  Each starts with a directive on a line  by  itself.   A  charset
       subsection  is  mandatory  unless the associated DESC file contains the
       unicode directive.  Another subsection, kernpairs, is optional.

       The directive charset starts the character set subsection.  (For  type‐
       setter  devices,  this  directive is misnamed since it starts a list of
       glyphs, not characters.)  It precedes a series of  glyph  descriptions,
       one  per  line.   Each such glyph description comprises a set of fields
       separated by spaces or tabs and organized as follows.

              name metrics type code [entity‐name] [-- comment]

       name identifies the glyph: if name is a printable character c, it  cor‐
       responds to the troff ordinary character c.  If name is a multi‐charac‐
       ter sequence not beginning with \, it corresponds to the GNU troff spe‐
       cial  character  escape sequence “\[name]”.  A name consisting of three
       minus signs, “---”, indicates that the glyph is  unnamed:  such  glyphs
       can  be  accessed  only  by the \N escape sequence in troff.  A special
       character named “---” can still be defined using .char and similar  re‐
       quests.  The name “\-” defines the minus sign glyph.  Finally, name can
       be the horizontal motion escape sequences, \| and \^ (“thin” and “hair”
       spaces,  respectively),  in  which case only the width metric described
       below is applied; a font can thus customize the widths of these spaces.

       The form of the metrics field is as follows (on one  line;  it  may  be
       broken here for readability).

              width[,[height[,[depth[,[italic‐correction[,[
              left‐italic‐correction[,[subscript‐correction]]]]]]]]]]

       There  must  not  be  any  spaces, tabs, or newlines between these sub‐
       fields, which are in basic units expressed as  decimal  integers.   Un‐
       specified  subfields default to 0.  Since there is no associated binary
       format, these values are not required to fit into the C  language  data
       type char as they are in AT&T device‐independent troff.

       The  width  subfield gives the width of the glyph.  The height subfield
       gives the height of the glyph (upwards is positive); if  a  glyph  does
       not extend above the baseline, it should be given a zero height, rather
       than  a  negative  height.   The  depth subfield gives the depth of the
       glyph, that is, the distance below the baseline to which the glyph  ex‐
       tends  (downwards  is  positive);  if a glyph does not extend below the
       baseline, it should be given a  zero  depth,  rather  than  a  negative
       depth.   Italic corrections are relevant to glyphs in italic or oblique
       styles.  The italic‐correction is the amount of space  that  should  be
       added  after  an oblique glyph to be followed immediately by an upright
       glyph.  The left‐italic‐correction is the amount of space  that  should
       be  added  before an oblique glyph to be preceded immediately by an up‐
       right glyph.  The subscript‐correction is  the  amount  of  space  that
       should  be  added after an oblique glyph to be followed by a subscript;
       it should be less than the italic correction.

       For fonts used with typesetting devices, the type field gives  a  feat‐
       ural  description  of the glyph: it is a bit mask recording whether the
       glyph is an ascender, descender, both, or neither.  When  a  \w  escape
       sequence  is  interpolated, these values are bitwise or‐ed together for
       each glyph and stored in the ct register.   In  font  descriptions  for
       terminal  devices,  all glyphs might have a type of zero, regardless of
       their appearance.

       0      means the glyph lies entirely between the baseline and  a  hori‐
              zontal line at the “x‐height” of the font, as with “a”, “c”, and
              “x”;

       1      means the glyph descends below the baseline, like “p”;

       2      means  the  glyph ascends above the font’s x‐height, like “A” or
              “b”); and

       3      means the glyph is both an ascender and a descender—this is true
              of parentheses in some fonts.

       The code field gives a numeric identifier that the  postprocessor  uses
       to  render  the  glyph.  The glyph can be specified to troff using this
       code by means of the \N escape sequence.  The code can be  any  integer
       (that  is,  any  integer parsable by the C standard library’s strtol(3)
       function).

       The entity‐name field defines an identifier  for  the  glyph  that  the
       postprocessor  uses  to  print the troff glyph name.  This field is op‐
       tional; it was introduced so that the grohtml output driver  could  en‐
       code its character set.  For example, the glyph \[Po] is represented by
       “&pound;” in HTML 4.0.  For efficiency, these data are now compiled di‐
       rectly into grohtml.  grops uses the field to build sub‐encoding arrays
       for  PostScript fonts containing more than 256 glyphs.  Anything on the
       line after the entity‐name field or “--” is ignored.

       A line in the charset section can also have the form
              name "
       identifying name as another name for the glyph mentioned in the preced‐
       ing line.  Such aliases can be chained.

       The directive kernpairs starts a list of kerning adjustments to be made
       to adjacent glyph pairs from this font.   It  contains  a  sequence  of
       lines formatted as follows.
              g1 g2 n
       The  foregoing  means  that when glyph g1 is typeset immediately before
       g2, the space between them should be  increased  by  n.   Most  kerning
       pairs should have a negative value for n.

Files
       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

       /usr/share/groff/1.23.0/font/devname/F
              describes the font known as F on device name.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       “Troff  User’s  Manual” by Joseph F. Ossanna, 1976 (revised by Brian W.
       Kernighan, 1992), AT&T Bell Laboratories  Computing  Science  Technical
       Report No. 54, widely called simply “CSTR #54”, documents the language,
       device and font description file formats, and device‐independent output
       format referred to collectively in groff documentation as “AT&T troff”.

       “A Typesetter‐independent TROFF” by Brian W. Kernighan, 1982, AT&T Bell
       Laboratories  Computing Science Technical Report No. 97, provides addi‐
       tional insights into the device and font description file  formats  and
       device‐independent output format.

       groff(1), subsection “Utilities”, lists programs available for describ‐
       ing  fonts  in  a variety of formats such that groff output drivers can
       use them.

       troff(1) documents the default device and font description file  search
       path.

       groff_out(5), addftinfo(1)

groff 1.23.0                      2 July 2023                    groff_font(5)
───────────────────────────────────────────────────────────────────────────────
groff_out(5)                  File Formats Manual                 groff_out(5)

Name
       groff_out - GNU roff intermediate output format

Description
       The  fundamental operation of the troff(1) formatter is the translation
       of the groff(7) input language into a series of instructions  concerned
       primarily  with  placing  glyphs or geometric objects at specific posi‐
       tions on a rectangular page.  In the  following  discussion,  the  term
       command  refers  to  this  intermediate  output  language, never to the
       groff(7) language intended for use by document  authors.   Intermediate
       output commands comprise several categories: glyph output; font, color,
       and text size selection; motion of the printing position; page advance‐
       ment;  drawing  of geometric primitives; and device control commands, a
       catch‐all for other operations.  The last includes directives to  start
       and stop output, identify the intended output device, and embed URL hy‐
       perlinks in supported output formats.

       Because  the front‐end command groff(1) is a wrapper that normally runs
       the troff formatter to generate intermediate output and an output  dri‐
       ver  (“postprocessor”)  to  consume it, users normally do not encounter
       this language.  The groff program’s -Z option  inhibits  postprocessing
       such  that  this  intermediate  output  is  sent to the standard output
       stream as when troff is run manually.

       groff’s intermediate output facilitates the development of output  dri‐
       vers  and  other postprocessors by offering a common programming inter‐
       face.  It is an extension of the page description language developed by
       Brian Kernighan for AT&T device‐independent troff circa 1980.  Where  a
       distinction  is  necessary,  we will say “troff output” to describe the
       output of GNU troff, and “intermediate output” to denote  the  language
       accepted by the parser implemented in groff’s internal C++ library used
       by most of its output drivers.

Language concepts
       During the run of troff, the roff input is cracked down to the informa‐
       tion on what has to be printed at what position on the intended device.
       So  the  language of the intermediate output format can be quite small.
       Its only elements are commands with or without arguments.  In this doc‐
       ument, the term “command” always refers to the intermediate output lan‐
       guage, never to the roff language used for document formatting.   There
       are commands for positioning and text writing, for drawing, and for de‐
       vice controlling.

   Separation
       Classical  troff  output  had  strange requirements on whitespace.  The
       groff output parser, however, is smart about whitespace  by  making  it
       maximally  optional.   The whitespace characters, i.e., the tab, space,
       and newline characters, always have a syntactical  meaning.   They  are
       never printable because spacing within the output is always done by po‐
       sitioning commands.

       Any  sequence of space or tab characters is treated as a single syntac‐
       tical space.  It separates commands and arguments, but is only required
       when there would occur a clashing between the command code and the  ar‐
       guments  without  the  space.   Most  often, this happens when variable
       length command names, arguments, argument lists,  or  command  clusters
       meet.   Commands  and  arguments with a known, fixed length need not be
       separated by syntactical space.

       A line break is a syntactical element, too.  Every command argument can
       be followed by whitespace, a comment, or a newline character.   Thus  a
       syntactical  line  break  is defined to consist of optional syntactical
       space that is optionally followed by a comment, and a  newline  charac‐
       ter.

       The  normal commands, those for positioning and text, consist of a sin‐
       gle letter taking a fixed number of arguments.  For historical reasons,
       the parser allows stacking of such commands on the same line, but  for‐
       tunately, in groff intermediate output, every command with at least one
       argument  is  followed  by a line break, thus providing excellent read‐
       ability.

       The other commands — those for drawing and device controlling — have  a
       more complicated structure; some recognize long command names, and some
       take  a variable number of arguments.  So all D and x commands were de‐
       signed to request a syntactical line break after their  last  argument.
       Only  one  command, ‘x X’ has an argument that can stretch over several
       lines, all other commands must have all of their arguments on the  same
       line  as  the  command,  i.e., the arguments may not be split by a line
       break.

       Lines containing only spaces and/or a comment are treated as empty  and
       ignored.

   Argument units
       Some commands accept integer arguments that represent measurements, but
       the  scaling  units  of  the formatter’s language are never used.  Most
       commands assume a scaling unit of “u” (basic units), and others use “z”
       (scaled points); These are defined by the parameters specified  in  the
       device’s  DESC  file; see groff_font(5) and, for more on scaling units,
       groff(7) and Groff: The GNU Implementation of troff, the groff  Texinfo
       manual.  Color‐related commands use dimensionless integers.

       Note  that  single  characters  can have the eighth bit set, as can the
       names of fonts and special characters (this is, glyphs).  The names  of
       glyphs  and  fonts  can  be of arbitrary length.  A glyph that is to be
       printed will always be in the current font.

       A string argument is always terminated by the next whitespace character
       (space, tab, or newline); an embedded # character is regarded  as  part
       of the argument, not as the beginning of a comment command.  An integer
       argument  is  already terminated by the next non‐digit character, which
       then is regarded as the first character of the next  argument  or  com‐
       mand.

   Document parts
       A  correct intermediate output document consists of two parts, the pro‐
       logue and the body.

       The task of the prologue is to set the general device parameters  using
       three  exactly specified commands.  The groff prologue is guaranteed to
       consist of the following three lines (in that order):

              x T device
              x res n h v
              x init

       with the arguments set as outlined in subsection “Device  Control  Com‐
       mands”  below.   However, the parser for the intermediate output format
       is able to swallow additional whitespace and comments as well.

       The body is the main section for processing the document data.  Syntac‐
       tically, it is a sequence of any commands different from the ones  used
       in  the prologue.  Processing is terminated as soon as the first x stop
       command is encountered; the last line of any groff intermediate  output
       always contains such a command.

       Semantically,  the  body  is page oriented.  A new page is started by a
       p command.  Positioning, writing, and drawing commands are always  done
       within  the  current page, so they cannot occur before the first p com‐
       mand.  Absolute positioning (by the H and V commands) is done  relative
       to the current page, all other positioning is done relative to the cur‐
       rent location within this page.

Command reference
       This  section describes all intermediate output commands, the classical
       commands as well as the groff extensions.

   Comment command
       #anything⟨line‐break⟩
              A comment.  Ignore any characters from the # character up to the
              next newline.  Each comment can be preceded by arbitrary syntac‐
              tical space; every command can be terminated by a comment.

   Simple commands
       The commands in this subsection have a command  code  consisting  of  a
       single character, taking a fixed number of arguments.  Most of them are
       commands  for  positioning  and text writing.  These commands are smart
       about whitespace.  Optionally, syntactical space can  be  inserted  be‐
       fore,  after, and between the command letter and its arguments.  All of
       these commands are stackable, i.e., they can be preceded by other  sim‐
       ple  commands or followed by arbitrary other commands on the same line.
       A separating syntactical space is necessary only when two integer argu‐
       ments would clash or if the preceding argument ends with a string argu‐
       ment.

       C id⟨white‐space⟩
              Typeset the glyph of the special character id.  Trailing syntac‐
              tical space is necessary to allow special character names of ar‐
              bitrary length.  The drawing position is not advanced.

       c c    Typeset the glyph of the ordinary character  character  c.   The
              drawing position is not advanced.

       f n    Select the font mounted at position n.  n cannot be negative.

       H n    Horizontally move the drawing position to n basic units from the
              left edge of the page.  n cannot be negative.

       h n    Move  the  drawing position right n basic units.  AT&T troff al‐
              lowed negative n; GNU troff does not produce  such  values,  but
              groff’s output driver library handles them.

       m scheme [component ...]
              Select  the stroke color using the components in the color space
              scheme.  Each component is an integer between 0 and 65536.   The
              quantity of components and their meanings vary with each scheme.
              This command is a groff extension.

              mc cyan magenta yellow
                     Use  the  CMY color scheme with components cyan, magenta,
                     and yellow.

              md     Use the default  color  (no  components;  black  in  most
                     cases).

              mg gray
                     Use a grayscale color scheme with a component ranging be‐
                     tween 0 (black) and 65536 (white).

              mk cyan magenta yellow black
                     Use  the CMYK color scheme with components cyan, magenta,
                     yellow, and black.

              mr red green blue
                     Use the RGB color scheme with components red, green,  and
                     blue.

       N n    Typeset  the  glyph with index n in the current font.  n is nor‐
              mally a non‐negative integer.  The drawing position is  not  ad‐
              vanced.   The html and xhtml devices use this command with nega‐
              tive n to produce unbreakable space; the absolute value of n  is
              taken and interpreted in basic units.

       n b a  Indicate  a  break.   No  action  is  performed;  the command is
              present to make the output more easily parsed.  The  integers  b
              and  a  describe the vertical space amounts before and after the
              break, respectively.  GNU troff issues this command but  groff’s
              output driver library ignores it.  See v and V.

       p n    Begin  a  new page, setting its number to n.  Each page is inde‐
              pendent, even from those using the same  number.   The  vertical
              drawing  position  is  set  to 0.  All positioning, writing, and
              drawing commands are interpreted in the context of a page, so  a
              p command must precede them.

       s n    Set  type  size  to n scaled points (unit z in GNU troff).  AT&T
              troff used unscaled points (p) instead; see section “Compatibil‐
              ity” below.

       t xyz...⟨white‐space⟩
       t xyz... dummy‐arg⟨white‐space⟩
              Typeset word xyz; that is, set a  sequence  of  ordinary  glyphs
              named  x,  y,  z,  ..., terminated by a space or newline; an op‐
              tional second integer argument is ignored (this allows the  for‐
              matter  to generate an even number of arguments).  Each glyph is
              set at the current drawing position, and the  position  is  then
              advanced  horizontally by the glyph’s width.  A glyph’s width is
              read from its metrics in the font description  file,  scaled  to
              the current type size, and rounded to a multiple of the horizon‐
              tal motion quantum.  Use the C command to emplace glyphs of spe‐
              cial characters.  The t command is a groff extension and is out‐
              put  only  for devices whose DESC file contains the tcommand di‐
              rective; see groff_font(5).

       u n xyz...
       u xyz... dummy‐arg⟨white‐space⟩
              Typeset word xyz with track kerning.  As t,  but  after  placing
              each  glyph,  the  drawing position is further advanced horizon‐
              tally by n basic units.  The u command is a groff extension  and
              is output only for devices whose DESC file contains the tcommand
              directive; see groff_font(5).

       V n    Vertically  move  the drawing position to n basic units from the
              top edge of the page.  n cannot be negative.

       v n    Move the drawing position down n basic units.   AT&T  troff  al‐
              lowed  negative  n;  GNU troff does not produce such values, but
              groff’s output driver library handles them.

       w      Indicate an inter‐word space.  No action is performed; the  com‐
              mand is present to make the output more easily parsed.  Only ad‐
              justable,  breakable inter‐word spaces are thus described; those
              resulting from \~ or horizontal motion escape sequences are not.
              GNU troff issues this command but groff’s output driver  library
              ignores it.  See h and H.

   Graphics commands
       Each graphics or drawing command in the intermediate output starts with
       the  letter  D followed by one or two characters that specify a subcom‐
       mand; this is followed by a fixed or variable number of  integer  argu‐
       ments  that are separated by a single space character.  A D command may
       not be followed by another command on the same line (apart from a  com‐
       ment), so each D command is terminated by a syntactical line break.

       troff output follows the classical spacing rules (no space between com‐
       mand and subcommand, all arguments are preceded by a single space char‐
       acter),  but  the parser allows optional space between the command let‐
       ters and makes the space before the first argument optional.  As usual,
       each space can be any sequence of tab and space characters.

       Some graphics commands can take a variable  number  of  arguments.   In
       this  case,  they  are  integers  representing a size measured in basic
       units u.  The h arguments stand for horizontal distances where positive
       means right, negative left.  The v arguments stand  for  vertical  dis‐
       tances where positive means down, negative up.  All these distances are
       offsets relative to the current location.

       Unless  indicated otherwise, each graphics command directly corresponds
       to a similar groff \D escape sequence; see groff(7).

       Unknown D commands are assumed to be  device‐specific.   Its  arguments
       are  parsed as strings; the whole information is then sent to the post‐
       processor.

       In the following command reference,  the  syntax  element  ⟨line‐break⟩
       means  a  syntactical  line break as defined in subsection “Separation”
       above.

       D~ h1 v1 h2 v2 ... hn vn⟨line‐break⟩
              Draw B‐spline from current position to offset (h1, v1), then  to
              offset  (h2, v2)  if  given,  etc., up to (hn, vn). This command
              takes a variable number of argument pairs; the current  position
              is moved to the terminal point of the drawn curve.

       Da h1 v1 h2 v2⟨line‐break⟩
              Draw  arc from current position to (h1, v1)+(h2, v2) with center
              at (h1, v1); then move the current position to the  final  point
              of the arc.

       DC d⟨line‐break⟩
       DC d dummy‐arg⟨line‐break⟩
              Draw a solid circle using the current fill color with diameter d
              (integer  in  basic  units u) with leftmost point at the current
              position; then move the current position to the rightmost  point
              of  the  circle.  An optional second integer argument is ignored
              (this allows the formatter to generate an even number  of  argu‐
              ments).  This command is a groff extension.

       Dc d⟨line‐break⟩
              Draw circle line with diameter d (integer in basic units u) with
              leftmost  point  at  the current position; then move the current
              position to the rightmost point of the circle.

       DE h v⟨line‐break⟩
              Draw a solid ellipse in the current fill color with a horizontal
              diameter of h and a vertical diameter of v (both integers in ba‐
              sic units u) with the leftmost point at  the  current  position;
              then  move  to the rightmost point of the ellipse.  This command
              is a groff extension.

       De h v⟨line‐break⟩
              Draw an outlined ellipse with a horizontal diameter of h  and  a
              vertical diameter of v (both integers in basic units u) with the
              leftmost  point  at current position; then move to the rightmost
              point of the ellipse.

       DF color‐scheme [component ...]⟨line‐break⟩
              Set fill color for solid drawing objects using  different  color
              schemes;  the  analogous  command for setting the color of text,
              line graphics, and the outline of graphic  objects  is  m.   The
              color  components  are  specified as integer arguments between 0
              and 65536.  The number of color  components  and  their  meaning
              vary for the different color schemes.  These commands are gener‐
              ated  by  the  groff escape sequences \D'F ...’  and \M (with no
              other corresponding graphics commands).  This command is a groff
              extension.

              DFc cyan magenta yellow⟨line‐break⟩
                     Set fill color for solid drawing objects  using  the  CMY
                     color  scheme,  having  the  3 color components cyan, ma‐
                     genta, and yellow.

              DFd ⟨line‐break⟩
                     Set fill color for solid drawing objects to  the  default
                     fill color value (black in most cases).  No component ar‐
                     guments.

              DFg gray⟨line‐break⟩
                     Set  fill color for solid drawing objects to the shade of
                     gray given by the argument, an integer between 0  (black)
                     and 65536 (white).

              DFk cyan magenta yellow black⟨line‐break⟩
                     Set  fill  color for solid drawing objects using the CMYK
                     color scheme, having the 4  color  components  cyan,  ma‐
                     genta, yellow, and black.

              DFr red green blue⟨line‐break⟩
                     Set  fill  color  for solid drawing objects using the RGB
                     color scheme, having the 3 color components  red,  green,
                     and blue.

       Df n⟨line‐break⟩
              The argument n must be an integer in the range -32767 to 32767.

              0≤n≤1000
                     Set  the  color  for  filling  solid drawing objects to a
                     shade of gray, where 0 corresponds to solid  white,  1000
                     (the  default)  to  solid black, and values in between to
                     intermediate shades of gray; this is obsoleted by command
                     DFg.

              n<0 or n>1000
                     Set the filling color to the color that is currently  be‐
                     ing  used  for  the  text and the outline, see command m.
                     For example, the command sequence

                            mg 0 0 65536
                            Df -1

                     sets all colors to blue.

              This command is a groff extension.

       Dl h v⟨line‐break⟩
              Draw line from current position to offset  (h, v)  (integers  in
              basic  units  u);  then  set  current position to the end of the
              drawn line.

       Dp h1 v1 h2 v2 ... hn vn⟨line‐break⟩
              Draw a polygon line from current position  to  offset  (h1, v1),
              from  there to offset (h2, v2), etc., up to offset (hn, vn), and
              from there back to the starting position.  For  historical  rea‐
              sons, the position is changed by adding the sum of all arguments
              with  odd  index to the current horizontal position and the even
              ones to the vertical position.  Although this doesn’t make sense
              it is kept for compatibility.  This command is  a  groff  exten‐
              sion.

       DP h1 v1 h2 v2 ... hn vn⟨line‐break⟩
              The same macro as the corresponding Dp command with the same ar‐
              guments,  but  draws  a  solid polygon in the current fill color
              rather than an outlined polygon.  The position is changed in the
              same way as with Dp.  This command is a groff extension.

       Dt n⟨line‐break⟩
              Set the current  line  thickness  to  n  (an  integer  in  basic
              units  u)  if  n>0;  if  n=0  select the smallest available line
              thickness; otherwise, the line thickness is made proportional to
              the type size, which is the default.   For  historical  reasons,
              the horizontal position is changed by adding the argument to the
              current  horizontal position, while the vertical position is not
              changed.  Although this doesn’t make sense, it is kept for  com‐
              patibility.  This command is a groff extension.

   Device control commands
       Each  device  control  command  starts  with the letter x followed by a
       space character (optional or arbitrary space/tab in groff) and  a  sub‐
       command  letter  or  word; each argument (if any) must be preceded by a
       syntactical space.  All x commands are terminated by a syntactical line
       break; no device control command can be followed by another command  on
       the same line (except a comment).

       The  subcommand is basically a single letter, but to increase readabil‐
       ity, it can be written as a word, i.e., an arbitrary sequence of  char‐
       acters  terminated  by  the next tab, space, or newline character.  All
       characters of the subcommand word but the  first  are  simply  ignored.
       For example, troff outputs the initialization command x i as x init and
       the  resolution command x r as x res.  But writings like x i_like_groff
       and x roff_is_groff are accepted as well to mean the same commands.

       In the following, the syntax element ⟨line‐break⟩ means  a  syntactical
       line break as defined in subsection “Separation” above.

       xF name⟨line‐break⟩
              (Filename control command)
              Use  name as the intended name for the current file in error re‐
              ports.  This is useful for remembering the  original  file  name
              when groff uses an internal piping mechanism.  The input file is
              not changed by this command.  This command is a groff extension.

       xf n s⟨line‐break⟩
              (font control command)
              Mount font position n (a non‐negative integer) with font named s
              (a text word); see groff_font(5).

       xH n⟨line‐break⟩
              (Height control command)
              Set  character  height  to  n  (a  positive  integer  in  scaled
              points z).  Classical troff used the unit  points  (p)  instead;
              see section “Compatibility” below.

       xi ⟨line‐break⟩
              (init control command)
              Initialize device.  This is the third command of the prologue.

       xp ⟨line‐break⟩
              (pause control command)
              Parsed but ignored.  The classical documentation reads pause de‐
              vice, can be restarted.

       xr n h v⟨line‐break⟩
              (resolution control command)
              Resolution is n, while h is the minimal horizontal motion, and v
              the minimal vertical motion possible with this device; all argu‐
              ments  are positive integers in basic units u per inch.  This is
              the second command of the prologue.

       xS n⟨line‐break⟩
              (Slant control command)
              Set slant to n degrees (an integer in basic units u).

       xs ⟨line‐break⟩
              (stop control command)
              Terminates the processing of the current  file;  issued  as  the
              last command of any intermediate troff output.

       xt ⟨line‐break⟩
              (trailer control command)
              Generate  trailer  information,  if any.  In groff, this is cur‐
              rently ignored.

       xT xxx⟨line‐break⟩
              (Typesetter control command)
              Set the name of the output driver to xxx,  a  sequence  of  non‐
              whitespace  characters  terminated  by whitespace.  The possible
              names correspond to those of groff’s -T  option.   This  is  the
              first command of the prologue.

       xu n⟨line‐break⟩
              (underline control command)
              Configure  underlining  of spaces.  If n is 1, start underlining
              of spaces; if n is 0,  stop  underlining  of  spaces.   This  is
              needed  for  the  cu request in nroff mode and is ignored other‐
              wise.  This command is a groff extension.

       xX anything⟨line‐break⟩
              (X‐escape control command)
              Send string anything uninterpreted to the device.  If  the  line
              following  this  command  starts with a + character this line is
              interpreted as a continuation line in the following sense.   The
              + is ignored, but a newline character is sent instead to the de‐
              vice,  the rest of the line is sent uninterpreted.  The same ap‐
              plies to all following lines until the first character of a line
              is not a + character.  This command is generated  by  the  groff
              escape  sequence \X.  The line‐continuing feature is a groff ex‐
              tension.

   Obsolete command
       In classical troff output, emitting a single glyph was mostly done by a
       very strange command that combined a horizontal move and  the  printing
       of  a  glyph.   It  didn’t have a command code, but is represented by a
       3‐character argument consisting of exactly 2 digits and a character.

       ddc    Move right dd (exactly two decimal digits) basic units  u,  then
              print glyph with single‐letter name c.

              In  groff,  arbitrary  syntactical  space around and within this
              command is allowed to be added.  Only when a  preceding  command
              on the same line ends with an argument of variable length a sep‐
              arating space is obligatory.  In classical troff, large clusters
              of  these  and  other commands were used, mostly without spaces;
              this made such output almost unreadable.

       For modern high‐resolution devices, this command does  not  make  sense
       because the width of the glyphs can become much larger than two decimal
       digits.  In groff, it is used only for output to the X75, X75-12, X100,
       and  X100-12 devices.  For others, the commands t and u provide greater
       functionality and superior troubleshooting capacity.

Postprocessing
       The roff postprocessors are programs that have the  task  to  translate
       the  intermediate output into actions that are sent to a device.  A de‐
       vice can be some piece of hardware such as a  printer,  or  a  software
       file  format suitable for graphical or text processing.  The groff sys‐
       tem provides powerful means that make the  programming  of  such  post‐
       processors an easy task.

       There  is  a  library  function that parses the intermediate output and
       sends the information obtained to the device via  methods  of  a  class
       with a common interface for each device.  So a groff postprocessor must
       only  redefine  the methods of this class.  For details, see the refer‐
       ence in section “Files” below.

Example
       This section presents the intermediate output generated from  the  same
       input  for  three  different  devices.   The input is the sentence hell
       world fed into groff on the command line.

       • High‐resolution device ps

         shell> echo "hell world" | groff -Z -T ps

         x T ps
         x res 72000 1 1
         x init
         p1
         x font 5 TR
         f5
         s10000
         V12000
         H72000
         thell
         wh2500
         tw
         H96620
         torld
         n12000 0
         x trailer
         V792000
         x stop

       This output can be fed into the postprocessor grops(1) to get its  rep‐
       resentation  as  a  PostScript file, or gropdf(1) to output directly to
       PDF.

       • Low‐resolution device latin1

         This is similar to the high‐resolution device except that  the  posi‐
         tioning is done at a minor scale.  Some comments (lines starting with
         #)  were added for clarification; they were not generated by the for‐
         matter.

         shell> "hell world" | groff -Z -T latin1

         # prologue
         x T latin1
         x res 240 24 40
         x init
         # begin a new page
         p1
         # font setup
         x font 1 R
         f1
         s10
         # initial positioning on the page
         V40
         H0
         # write text 'hell'
         thell
         # inform about a space, and do it by a horizontal jump
         wh24
         # write text 'world'
         tworld
         # announce line break, but do nothing because ...
         n40 0
         # ... the end of the document has been reached
         x trailer
         V2640
         x stop

       This output can be fed into the postprocessor grotty(1) to get  a  for‐
       matted text document.

       • Classical style output

         As  a  computer  monitor has a very low resolution compared to modern
         printers the intermediate output for the X devices can use the  jump‐
         and‐write command with its 2‐digit displacements.

         shell> "hell world" | groff -Z -T X100

         x T X100
         x res 100 1 1
         x init
         p1
         x font 5 TR
         f5
         s10
         V16
         H100
         # write text with old‐style jump‐and‐write command
         ch07e07l03lw06w11o07r05l03dh7
         n16 0
         x trailer
         V1100
         x stop

       This   output  can  be  fed  into  the  postprocessor  xditview(1x)  or
       gxditview(1) for displaying in X.

       Due to the obsolete jump‐and‐write command, the text  clusters  in  the
       classical output are almost unreadable.

Compatibility
       The intermediate output language of the classical troff was first docu‐
       mented in [CSTR #97].  The groff intermediate output format is compati‐
       ble with this specification except for the following features.

       • The classical quasi device independence is not yet implemented.

       • The  old  hardware was very different from what we use today.  So the
         groff devices are also fundamentally different from the ones in clas‐
         sical troff.  For example, the classical PostScript device was called
         post and had a resolution of 720 units per inch, while groff’s ps de‐
         vice has a resolution of 72000 units per inch.  Maybe, by  implement‐
         ing  some  rescaling  mechanism similar to the classical quasi device
         independence, these could be integrated into modern groff.

       • The B‐spline command D~ is correctly handled by the intermediate out‐
         put parser, but the drawing routines aren’t implemented  in  some  of
         the postprocessor programs.

       • The  argument  of the commands s and x H has the implicit unit scaled
         point z in groff, while classical troff had point (p).  This isn’t an
         incompatibility, but a compatible extension, for both units  coincide
         for  all devices without a sizescale parameter, including all classi‐
         cal and the groff  text  devices.   The  few  groff  devices  with  a
         sizescale  parameter  either  did not exist, had a different name, or
         seem to have had a different resolution.  So conflicts with classical
         devices are very unlikely.

       • The position changing after the commands Dp, DP, and Dt is illogical,
         but as old versions of groff used this feature it is kept for compat‐
         ibility reasons.

       The differences between groff and classical  troff  are  documented  in
       groff_diff(7).

Files
       /usr/share/groff/1.23.0/font/devname/DESC
              describes the output device name.

Authors
       James  Clark  wrote  an early version of this document, which described
       only the differences between  AT&T  device‐independent  troff’s  output
       format  and  that  of  GNU  roff.   The  present version was completely
       rewritten in 2001 by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.

See also
       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is the primary groff manual.  You can browse it interactively
       with “info groff”.

       “Troff User’s Manual” by Joseph F. Ossanna, 1976 (revised by  Brian  W.
       Kernighan,  1992),  AT&T  Bell Laboratories Computing Science Technical
       Report No. 54, widely called simply “CSTR #54”, documents the language,
       device and font description file formats, and device‐independent output
       format referred to collectively in groff documentation as “AT&T troff”.

       “A Typesetter‐independent TROFF” by Brian W. Kernighan, 1982, AT&T Bell
       Laboratories Computing Science Technical Report No. 97, provides  addi‐
       tional  insights  into the device and font description file formats and
       device‐independent output format.

       groff(1)
              documents the -Z option and contains pointers to  further  groff
              documentation.

       groff(7)
              describes the groff language, including its escape sequences and
              system of units.

       groff_font(5)
              details the device scaling parameters of device DESC files.

       troff(1)
              generates  the device‐independent intermediate output documented
              here.

       roff(7)
              presents historical aspects and the general  structure  of  roff
              systems.

       groff_diff(7)
              enumerates  differences between the intermediate output produced
              by AT&T troff and that of groff.

       gxditview(1)
              is a viewer for intermediate output.

       Roff.js
              ⟨https://github.com/Alhadis/Roff.js/⟩ is a viewer for intermedi‐
              ate output written in JavaScript.

       grodvi(1), grohtml(1), grolbp(1), grolj4(1), gropdf(1),  grops(1),  and
       grotty(1) are groff postprocessors.

groff 1.23.0                      2 July 2023                     groff_out(5)
───────────────────────────────────────────────────────────────────────────────
groff_tmac(5)                 File Formats Manual                groff_tmac(5)

Name
       groff_tmac - macro files in the GNU roff typesetting system

Description
       Definitions of macros, strings, and registers for use in a roff(7) doc‐
       ument  can  be collected into macro files, roff input files designed to
       produce no output themselves but instead ease the preparation of  other
       roff  documents.   There  is  no syntactical difference between a macro
       file and any other roff document; only its  purpose  distinguishes  it.
       When  a macro file is installed at a standard location, named according
       to a certain convention, and suitable for use by a general audience, it
       is termed a macro package.  Macro packages can be loaded  by  supplying
       the -m option to troff(1) or a groff front end.

       Each  macro  package stores its macro, string, and register definitions
       in one or more tmac files.  This name originated in early Unix  culture
       as an abbreviation of “troff macros”.

       A  macro file must have a name in the form name.tmac (or tmac.name) and
       be placed in a “tmac directory” to be loadable with the -mname  option.
       Section  “Environment”  of  troff(1) lists these directories.  Alterna‐
       tively, a groff document requiring a macro file can load  it  with  the
       mso (“macro source”) request.

       Like  any  other  roff  document, a macro file can use the “so” request
       (“source”) to load further files relative to its own location.

       Macro files are named for their  most  noteworthy  application,  but  a
       macro  file  need  not  define  any  macros.  It can restrict itself to
       defining registers and strings or invoking other  groff  requests.   It
       can even be empty.

Macro packages
       Macro packages come in two varieties; those which assume responsibility
       for  page  layout  and  other critical functions (“major” or “full‐ser‐
       vice”) and those which do not  (“supplemental”  or  “auxiliary”).   GNU
       roff provides most major macro packages found in AT&T and BSD Unix sys‐
       tems,  an  additional full‐service package, and many supplemental pack‐
       ages.  Multiple full‐service macro packages cannot be used by the  same
       document.   Auxiliary packages can generally be freely combined, though
       attention to their use of the groff language name  spaces  for  identi‐
       fiers  (particularly registers, macros, strings, and diversions) should
       be paid.  Name space management was a  significant  challenge  in  AT&T
       troff; groff’s support for arbitrarily long identifiers affords few ex‐
       cuses  for  name  collisions, apart from attempts at compatibility with
       the demands of historical documents.

   Man pages
       an
       man    an is used to compose man pages in  the  format  originating  in
              Version  7  Unix  (1979).  It has a small macro interface and is
              widely used; see groff_man(7).

       doc
       mdoc   doc is used to compose man pages in the  format  originating  in
              4.3BSD‐Reno (1990).  It provides many more features than an, but
              is  also  larger,  more  complex, and not as widely adopted; see
              groff_mdoc(7).

       Because readers of man pages often do not know in advance which  macros
       are used to format a given document, a wrapper is available.

       andoc
       mandoc This  macro  file, specific to groff, recognizes whether a docu‐
              ment uses man or mdoc format and loads the  corresponding  macro
              package.   Multiple man pages, in either format, can be handled;
              andoc reloads each macro package as necessary.

   Full‐service packages
       The packages in this section provide a complete set of macros for writ‐
       ing documents of any kind, up to whole  books.   They  are  similar  in
       functionality; it is a matter of taste which one to use.

       me     The classical me macro package; see groff_me(7).

       mm     The semi‐classical mm macro package; see groff_mm(7).

       mom    The mom macro package, only available in groff.  As this was not
              based on other packages, it was freely designed as quite a nice,
              modern macro package.  See groff_mom(7).

       ms     The classical ms macro package; see groff_ms(7).

   Localization packages
       For  Western languages, the localization file sets the hyphenation mode
       and loads hyphenation patterns and exceptions.  Localization files  can
       also adjust the date format and provide translations of strings used by
       some  of the full‐service macro packages; alter the input encoding (see
       the next section); and change the amount of  additional  inter‐sentence
       space.   For Eastern languages, the localization file defines character
       classes and sets flags on them.  By default, troffrc loads  the  local‐
       ization file for English.

       trans  loads  localized  strings  used  by various macro packages after
              their localized forms have been prepared by a localization macro
              file.

       groff provides the following localization files.

       cs     Czech; localizes man, me, mm, mom, and ms.  Sets the  input  en‐
              coding to Latin‐2 by loading latin2.tmac.

       de
       den    German;  localizes man, me, mm, mom, and ms.  Sets the input en‐
              coding to Latin‐1 by loading latin1.tmac.

              de.tmac selects hyphenation patterns for  traditional  orthogra‐
              phy, and den.tmac does the same for the new orthography (“Recht‐
              schreibreform”).

       en     English.

       fr     French;  localizes man, me, mm, mom, and ms.  Sets the input en‐
              coding to Latin‐9 by loading latin9.tmac.

       it     Italian; localizes man, me, mm, mom, and ms.

       ja     Japanese.

       sv     Swedish; localizes man, me, mm, mom, and ms.  Sets the input en‐
              coding to Latin‐1 by loading latin1.tmac.  Some of the localiza‐
              tion of the mm package is handled separately; see groff_mmse(7).

       zh     Chinese.

   Input encodings
       latin1
       latin2
       latin5
       latin9 are various ISO 8859 input encodings  supported  by  groff.   On
              systems  using  ISO character encodings, groff loads latin1.tmac
              automatically  at  startup.   A  document  that  uses   Latin‐2,
              Latin‐5,  or Latin‐9 can specify one of these alternative encod‐
              ings.

       cp1047 provides support for EBCDIC‐based systems.  On those  platforms,
              groff loads cp1047.tmac automatically at startup.

       Because  different input character codes constitute valid GNU troff in‐
       put on ISO and EBCDIC systems, the latin macro files cannot be used  on
       EBCDIC systems, and cp1047 cannot be used on ISO systems.

   Auxiliary packages
       The  macro  packages  in  this section are not intended for stand‐alone
       use, but can add functionality to any other macro package or  to  plain
       (“raw”) groff documents.

       62bit  provides  macros  for  addition, multiplication, and division of
              62‐bit integers (allowing safe multiplication of  signed  31‐bit
              integers, for example).

       hdtbl  allows  the  generation  of tables using a syntax similar to the
              HTML table model.  This Heidelberger table macro package is  not
              a preprocessor, which can be useful if the contents of table en‐
              tries  are  determined  by macro calls or string interpolations.
              Compare to tbl(1).  It works only with the ps and pdf output de‐
              vices.  See groff_hdtbl(7).

       papersize
              enables the paper format to be set on the command line by giving
              a “-d paper=format” option to troff.  Possible values for format
              are the ISO and  DIN  formats  “A0–A6”,  “B0–B6”,  “C0–C6”,  and
              “D0–D6”;   the   U.S.   formats  “letter”,  “legal”,  “tabloid”,
              “ledger”, “statement”, and “executive”; and the envelope formats
              “com10”, “monarch”, and “DL”.  All formats, even those  for  en‐
              velopes,  are in portrait orientation: the length measurement is
              vertical.  Appending “l” (ell) to any of these denotes landscape
              orientation instead.  This macro file assumes one‐inch  horizon‐
              tal  margins,  and  sets  registers recognized by the groff man,
              mdoc, mm, mom, and ms packages to  configure  them  accordingly.
              If  you want different margins, you will need to use those pack‐
              ages’ facilities, or troff ll and/or po requests to adjust them.
              An output device typically requires command‐line options -p  and
              -l  to  override  the  paper dimensions and orientation, respec‐
              tively, defined in its DESC file; see subsection “Paper  format”
              of  groff(1).   This macro file is normally loaded at startup by
              the troffrc file when formatting for a typesetting  device  (but
              not a terminal).

       pdfpic provides  a  single macro, PDFPIC, to include a PDF graphic in a
              document using features of the pdf  output  driver.   For  other
              output  devices, PDFPIC calls PSPIC, with which it shares an in‐
              terface (see below).  This macro  file  is  normally  loaded  at
              startup by the troffrc file.

       pic    supplies  definitions  of the macros PS, PE, and PF, usable with
              the pic(1) preprocessor.  They center each picture.  Use  it  if
              your document does not use a full‐service macro package, or that
              package  does  not supply working pic macro definitions.  Except
              for man and mdoc, those provided with groff already do  so  (ex‐
              ception: mm employs the name PF for a different purpose).

       pspic  provides a macro, PSPIC, that includes a PostScript graphic in a
              document.   The  ps, dvi, html, and xhtml output devices support
              such inclusions; for all other drivers, the  image  is  replaced
              with  a  rectangular  border  of  the  same size.  pspic.tmac is
              loaded at startup by the troffrc file.

              Its syntax is as follows.

                     .PSPIC [-L|-R|-C|-I n] file [width [height]]

              file is the name of the PostScript file; width and  height  give
              the  desired  width and height of the image.  If neither a width
              nor a height argument is specified, the  image’s  natural  width
              (as given in the file’s bounding box) or the current line length
              is used as the width, whatever is smaller.  The width and height
              arguments  may  have scaling units attached; the default scaling
              unit is i.  PSPIC scales the graphic uniformly in the horizontal
              and vertical directions so that it is no more  than  width  wide
              and  height  high.   Option -C centers the graphic horizontally;
              this is the default.   -L  and  -R  left‐  and  right‐align  the
              graphic,  respectively.  -I indents the graphic by n (with a de‐
              fault scaling unit of m).

              To use PSPIC within a diversion, we recommend extending it  with
              the  following  code,  assuring  that the diversion’s width com‐
              pletely covers the image’s width.

                     .am PSPIC
                     .  vpt 0
                     \h'(\\n[ps-offset]u + \\n[ps-deswid]u)'
                     .  sp -1
                     .  vpt 1
                     ..

              Failure to load PSPIC’s image argument is not  an  error.   (The
              psbb  request  does  issue an error diagnostic.)  To make such a
              failure fatal, append to the pspic*error-hook macro.

                     .am pspic*error-hook
                     .  ab
                     ..

       ptx    provides a macro, xx, to format permuted index entries  as  pro‐
              duced  by the GNU ptx(1) program.  If your formatting needs dif‐
              fer, copy the macro into your document  and  adapt  it  to  your
              needs.

       rfc1345
              defines  special  character escape sequences named for the glyph
              mnemonics specified in RFC 1345 and the digraph table of the Vim
              text editor.  See groff_rfc1345(7).

       sboxes offers an interface to the “pdf: background” device control com‐
              mand supported by gropdf(1).  Using this package, groff ms docu‐
              ments can draw colored rectangles beneath any output.

              .BOXSTART SHADED color OUTLINED color INDENT size WEIGHT size
                     begins a box, where the argument after SHADED  gives  the
                     fill  color  and  that  after  OUTLINED the border color.
                     Omit the former to get a borderless filled  box  and  the
                     latter  for  a border with no fill.  The specified WEIGHT
                     is used if the box is OUTLINED.

                     INDENT precedes a value which leaves a  gap  between  the
                     border and the contents inside the box.

                     Each  color  must be a defined groff color name, and each
                     size a valid groff numeric expression.  The keyword/value
                     pairs can be specified in any order.

              Boxes can be stacked, so you can start a box within another box;
              usually the later boxes would be  smaller  than  the  containing
              box,  but  this  is not enforced.  When using BOXSTART, the left
              position is the current indent minus the INDENT in the  command,
              and  the  right position is the left position (calculated above)
              plus the current line length and twice the indent.

              .BOXSTOP
                     takes no parameters.  It closes the most recently started
                     box at the current vertical  position  after  adding  its
                     INDENT spacing.

              Your  groff  documents  can  conditionally  exercise  the sboxes
              macros.  The register GSBOX is defined if the package is loaded,
              and interpolates a true value if the pdf  output  device  is  in
              use.

              sboxes furthermore hooks into the groff_ms(7) package to receive
              notifications  when  footnotes are growing, so that it can close
              boxes on a page before footnotes are printed.  When that  condi‐
              tion  obtains, sboxes will close open boxes two points above the
              footnote separator and re‐open them on  the  next  page.   (This
              amount probably will not match the box’s INDENT.)

              See “Using PDF boxes with groff and the ms macros” ⟨file:///usr/
              share/doc/groff-1.23.0/msboxes.pdf⟩ for a demonstration.

       trace  aids  the  debugging  of groff documents by tracing macro calls.
              See groff_trace(7).

       www    defines   macros   corresponding   to   HTML   elements.     See
              groff_www(7).

Naming
       AT&T  nroff  and  troff  were implemented before the conventions of the
       modern C getopt(3) call evolved, and used a  naming  scheme  for  macro
       packages  that looks odd to modern eyes.  Macro packages were typically
       loaded using the -m option to the formatter; when directly followed  by
       its  argument without an intervening space, this looked like a long op‐
       tion preceded by a single minus—a sensation in the computer stone  age.
       Macro  packages  therefore  came to be known by names that started with
       the letter “m”, which was omitted from the name of the  macro  file  as
       stored  on  disk.  For example, the manuscript macro package was stored
       as tmac.s and loaded with the option -ms.

       groff commands permit space between an option and  its  argument.   The
       syntax  “groff  -m s” makes the macro file name more clear but may sur‐
       prise users familiar with the original  convention,  unaware  that  the
       package’s  “real”  name  was  “s” all along.  For such packages of long
       pedigree, groff accommodates different users’ expectations by supplying
       wrapper macro files that load  the  desired  file  with  mso  requests.
       Thus, all of “groff -m s”, “groff -m ms”, “groff -ms”, and “groff -mms”
       serve to load the manuscript macros.

       Wrappers  are  not  provided  for packages of more recent vintage, like
       www.tmac.

       As noted in passing above, AT&T troff named macro  files  in  the  form
       tmac.name.   It  has  since become conventional in operating systems to
       use a suffixed file name extension to suggest a file type or format.

Inclusion
       The traditional method of employing a macro package is to  specify  the
       -m  package  option  to the formatter, which then reads package’s macro
       file prior to any input files.  Historically, package was sought  in  a
       file  named  tmac.package  (that is, with a “tmac.” prefix).  GNU troff
       searches for package.tmac in the macro path; if not found, it looks for
       tmac.package instead, and vice versa.

       Alternatively, one could include a macro file by using the request “.so
       file‐name” in the document; file‐name is resolved relative to the loca‐
       tion of the input document.  GNU troff offers an  improved  feature  in
       the  similar  request “mso package‐file‐name”, which searches the macro
       path for package‐file‐name.  Because its argument is a file  name,  its
       “.tmac”  component  must be included for the file to be found; however,
       as a convenience, if opening it fails, mso strips any such  suffix  and
       tries again with a “tmac.” prefix, and vice versa.

       If  a  sourced  file requires preprocessing, for example if it includes
       tbl tables or eqn equations, the preprocessor soelim(1) must  be  used.
       This can be achieved with a pipeline or, in groff, by specifying the -s
       option to the formatter (or front end).  man(1) librarian programs gen‐
       erally call soelim automatically.  (Macro packages themselves generally
       do not require preprocessing.)

Writing macros
       A  roff(7)  document is a text file that is enriched by predefined for‐
       matting constructs, such as requests, escape  sequences,  strings,  nu‐
       meric  registers,  and macros from a macro package.  These elements are
       described in roff(7).

       To give a document a personal style, it is most useful  to  extend  the
       existing elements by defining some macros for repeating tasks; the best
       place  for  this is near the beginning of the document or in a separate
       file.

       Macros without arguments are just like strings.  But the full power  of
       macros  occurs when arguments are passed with a macro call.  Within the
       macro definition, the arguments are available as the  escape  sequences
       \$1,  ...,  \$9,  \$[...], \$*, and \$@, the name under which the macro
       was called is in \$0, and  the  number  of  arguments  is  in  register
       \n[.$]; see groff(7).

   Draft mode
       Writing groff macros is easy when the escaping mechanism is temporarily
       disabled.   In groff, this is done by enclosing the macro definition(s)
       within a pair of .eo and .ec requests.  Then the body in the macro def‐
       inition is just like a normal part of the document — text  enhanced  by
       calls  of  requests, macros, strings, registers, etc.  For example, the
       code above can be written in a simpler way by

              .eo
              .ds midpart was called with the following
              .de print_args
              \f[I]\$0\f[] \*[midpart] \n[.$] arguments:
              \$*
              ..
              .ec

       Unfortunately, draft mode cannot be used universally.  Although  it  is
       good  enough for defining normal macros, draft mode fails with advanced
       applications, such as indirectly defined strings, registers,  etc.   An
       optimal  way is to define and test all macros in draft mode and then do
       the backslash doubling as a final step; do not forget to remove the .eo
       request.

   Tips for macro definitions
       •      Start every line with a dot, for example, by using the groff re‐
              quest .nop for text lines, or write your own macro that  handles
              also text lines with a leading dot.

                     .de Text
                     .  if (\\n[.$] == 0) \
                     .    return
                     .  nop \)\\$*\)
                     ..

       •      Write  a comment macro that works both for copy and draft modes;
              since the escape character is off in draft mode,  trouble  might
              occur  when comment escape sequences are used.  For example, the
              following macro just ignores its arguments, so it  acts  like  a
              comment line:

                     .de c
                     ..
                     .c This is like a comment line.

       •      In  long  macro  definitions, make ample use of comment lines or
              almost‐empty lines (this is, lines which have a leading dot  and
              nothing else) for a better structuring.

       •      To  increase  readability,  use groff’s indentation facility for
              requests and macro calls (arbitrary whitespace after the leading
              dot).

   Diversions
       Diversions can be used to implement  quite  advanced  programming  con‐
       structs.   They  are comparable to pointers to large data structures in
       the C programming language, but their usage is quite different.

       In their simplest form, diversions are multi‐line strings,  but  diver‐
       sions  get  their power when used dynamically within macros.  The (for‐
       matted) information stored in a diversion can be retrieved  by  calling
       the diversion just like a macro.

       Most  of the problems arising with diversions can be avoided if you re‐
       member that diversions always store complete lines.   Using  diversions
       when the line buffer has not been flushed produces strange results; not
       knowing  this,  many  people get desperate about diversions.  To ensure
       that a diversion works, add line breaks at the  right  places.   To  be
       safe,  enclose  everything that has to do with diversions within a pair
       of line breaks; for example, by explicitly using  .br  requests.   This
       rule  should  be  applied to diversion definition, both inside and out‐
       side, and to all calls of diversions.  This is a bit of  overkill,  but
       it works nicely.

       (If  you really need diversions which should ignore the current partial
       line, use environments to save the current partial line and/or use  the
       .box request.)

       The  most  powerful  feature  using  diversions is to start a diversion
       within a macro definition and end it within another macro.  Then every‐
       thing between each call of this macro pair is stored within the  diver‐
       sion and can be manipulated from within the macros.

Authors
       This  document  was  written by Bernd Warken ⟨groff-bernd.warken-72@web
       .de⟩, Werner Lemberg ⟨wl@gnu.org⟩, and G. Branden  Robinson  ⟨g.branden
       .robinson@gmail.com⟩.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       The  Filesystem  Hierarchy  Standard ⟨https://wiki.linuxfoundation.org/
       lsb/fhs⟩ is maintained by the Linux Foundation.

       groff(1)
              is an overview of the groff system.

       groff_man(7),
       groff_mdoc(7),
       groff_me(7),
       groff_mm(7),
       groff_mom(7),
       groff_ms(7),
       groff_rfc1345(7),
       groff_trace(7),
               and
       groff_www(7)
              are groff macro packages.

       groff(7)
              summarizes the language recognized by GNU troff.

       troff(1)
              documents the default macro file search path.

groff 1.23.0                      2 July 2023                    groff_tmac(5)
───────────────────────────────────────────────────────────────────────────────
groff(7)               Miscellaneous Information Manual               groff(7)

Name
       groff - GNU roff language reference

Description
       groff is short for GNU roff, a free reimplementation of  the  AT&T  de‐
       vice‐independent troff typesetting system.  See roff(7) for a survey of
       and background on roff systems.

       This  document  is  intended as a reference.  The primary groff manual,
       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is  a  better resource for learners, containing many examples
       and much discussion.  It is written in Texinfo; you can browse  it  in‐
       teractively  with  “info  groff”.   Additional formats, including plain
       text,  HTML,  DVI,  and  PDF,  may  be  available  in   /usr/share/doc/
       groff-1.23.0.

       groff  is also a name for an extended dialect of the roff language.  We
       use “roff” to denote features that are universal, or nearly  so,  among
       implementations  of this family.  We apply the term “groff” to the lan‐
       guage documented here, the GNU implementation of  the  overall  system,
       the project that develops that system, and the command of that name.

       GNU  troff,  installed  on this system as troff(1), is the formatter: a
       program that reads device and font descriptions (groff_font(5)), inter‐
       prets the groff language expressed in text input files, and  translates
       that  input into a device‐independent output format (groff_out(5)) that
       is usually then post‐processed by an output  driver  to  produce  Post‐
       Script, PDF, HTML, DVI, or terminal output.

Input format
       Input  to  GNU troff is organized into lines separated by the Unix new‐
       line character (U+000A), and must be in one of two character  encodings
       it can recognize: IBM code page 1047 on EBCDIC systems, and ISO Latin‐1
       (8859‐1)  otherwise.   Use of ISO 646‐1991:IRV (“US‐ASCII”) or (equiva‐
       lently) the “Basic Latin” subset of ISO  10646  (“Unicode”)  is  recom‐
       mended;  see  groff_char(7).   The  preconv(1)  preprocessor transforms
       other encodings, including UTF‐8, to satisfy troff’s requirements.

Syntax characters
       Several input characters are syntactically significant to groff.

       .   A dot at the beginning of an input line marks it as a control line.
           It can also follow the .el and .nop requests, and the condition  in
           .if,  .ie,  and .while requests.  The control character invokes re‐
           quests and calls macros by the name that follows it.  The  .cc  re‐
           quest can change the control character.

       '   The  neutral  apostrophe  is the no‐break control character, recog‐
           nized where the control character is.  It  suppresses  the  (first)
           break  implied  by the .bp, .cf, .fi, .fl, .in, .nf, .rj, .sp, .ti,
           and .trf requests.  The requested operation  takes  effect  at  the
           next  break.  It makes .br nilpotent.  The no‐break control charac‐
           ter can be changed with the .c2 request.  When formatted,  “'”  may
           be typeset as a typographical quotation mark; use the \[aq] special
           character escape sequence to format a neutral apostrophe glyph.

       "   The neutral double quote can be used to enclose arguments to macros
           and  strings,  and  is required if those arguments contain space or
           tab characters.  In the .ds, .ds1, .as, and .as1 requests, an  ini‐
           tial neutral double quote in the second argument is stripped off to
           allow  embedding  of leading spaces.  To include a double quote in‐
           side a quoted argument, use the \[dq] special character escape  se‐
           quence (which also serves to typeset the glyph in text).

       \   A  backslash  introduces  an escape sequence.  The escape character
           can be changed with the .ec request; .eo disables  escape  sequence
           recognition.   Use  the  \[rs] special character escape sequence to
           format a backslash glyph, and \e to typeset the glyph of  the  cur‐
           rent escape character.

       (   An opening parenthesis is special only in certain escape sequences;
           when  recognized,  it introduces an argument of exactly two charac‐
           ters.  groff offers the more flexible square bracket syntax.

       [   An opening bracket is special only  in  certain  escape  sequences;
           when  recognized,  it  introduces an argument (list) of any length,
           not including a closing bracket.

       ]   A closing bracket is special only when an escape sequence using  an
           opening  bracket as an argument delimiter is being interpreted.  It
           ends the argument (list).

       Additionally, the Control+A character (U+0001) in text  is  interpreted
       as a leader (see below).

       Horizontal  white space characters are significant to groff, but trail‐
       ing spaces on text lines are ignored.

       space   Space characters separate  arguments  in  request  invocations,
               macro calls, and string interpolations.  In text, they separate
               words.   Multiple adjacent space characters in text cause groff
               to attempt end‐of‐sentence detection on the preceding word (and
               trailing punctuation).  The amount of space between  words  and
               sentences  is  controlled  by the .ss request.  When filling is
               enabled (the default), a line may be broken at a  space.   When
               adjustment  is enabled (the default), inter‐word spaces are ex‐
               panded until the output line reaches the configured length.  An
               adjustable but non‐breaking space is available with \~.  To get
               a space of fixed width, use one of the escape  sequences  ‘\  ’
               (the  escape character followed by a space), \0, \|, \^, or \h;
               see section “Escape sequences” below.

       newline In text, a newline puts an inter‐word  space  onto  the  output
               and,  if  filling is enabled, triggers end‐of‐sentence recogni‐
               tion on the preceding text.  See  section  “Line  continuation”
               below.

       tab     A  tab character in text causes the drawing position to advance
               to the next defined tab stop.

Tabs and leaders
       The formatter interprets input horizontal tab characters  (“tabs”)  and
       Control+A  characters  (“leaders”) into movements to the next tab stop.
       Tabs simply move to the next tab stop; leaders place enough periods  to
       fill  the space.  Tab stops are by default located every half inch mea‐
       sured from the drawing position corresponding to the beginning  of  the
       input  line;  see section “Page geometry” of roff(7).  Tabs and leaders
       do not cause breaks and therefore do not interrupt filling.  Tab  stops
       can  be  configured with the ta request, and tab and leader glyphs with
       the tc and lc requests, respectively.

Line continuation
       When filling is enabled, input and output line breaks generally do  not
       correspond.  The roff language therefore distinguishes input and output
       line continuation.

       A backslash \ immediately followed by a newline, sometimes discussed as
       \newline,  suppresses  the  effects  of that newline on the input.  The
       next input line thus retains the classification of its predecessor as a
       control or text line.  \newline is useful for managing line lengths  in
       the  input  during document maintenance; you can break an input line in
       the middle of a request invocation, macro  call,  or  escape  sequence.
       Input  line continuation is invisible to the formatter, with two excep‐
       tions: the | operator recognizes the new input line, and the input line
       counter register .c is incremented.

       The \c escape sequence continues an output line.  Nothing on the  input
       line  after  it is formatted.  In contrast to \newline, a line after \c
       is treated as a new input line, so a control character is recognized at
       its beginning.  The visual results depend on  whether  filling  is  en‐
       abled.   An  intervening control line that causes a break overrides \c,
       flushing out the pending output line in the usual  way.   The  register
       .int  contains  a  positive value if the last output line was continued
       with \c; this datum is associated with the environment.

Colors
       groff supports color output with a variety of color spaces and up to 16
       bits per channel.  Some devices, particularly terminals,  may  be  more
       limited.   When color support is enabled, two colors are current at any
       given time: the stroke color, with which  glyphs,  rules  (lines),  and
       geometric  objects  like  circles  and polygons are drawn, and the fill
       color, which can be used to paint the interior of  a  closed  geometric
       figure.   The  color,  defcolor, gcolor, and fcolor requests; \m and \M
       escape sequences; and .color, .m, and .M registers exercise color  sup‐
       port.

       Each  output  device has a color named “default”, which cannot be rede‐
       fined.  A device’s default stroke and fill colors are  not  necessarily
       the  same.  For the dvi, html, pdf, ps, and xhtml output devices, troff
       automatically loads a macro file defining many color names at  startup.
       By the same mechanism, the devices supported by grotty(1) recognize the
       eight  standard  ISO  6429/ECMA‐48  color names (also known vulgarly as
       “ANSI colors”).

Measurements
       Numeric parameters that specify measurements are expressed as  integers
       or decimal fractions with an optional scaling unit suffixed.  A scaling
       unit  is  a letter that immediately follows the last digit of a number.
       Digits after the decimal point are optional.

       Measurements are scaled by the scaling unit and stored internally (with
       any fractional part discarded) in basic units.  The  device  resolution
       can  therefore  be  obtained  by storing a value of “1i” to a register.
       The only constraint on the basic unit is that it is at least  as  small
       as any other unit.

       u      Basic unit.
       i      Inch; defined as 2.54 centimeters.
       c      Centimeter.
       p      Point;  a typesetter’s unit used for measuring type size.  There
              are 72 points to an inch.
       P      Pica; another typesetter’s unit.  There are 6 picas to  an  inch
              and 12 points to a pica.
       s, z   Scaled   points   and  multiplication  by  the  output  device’s
              sizescale parameter, respectively.
       f      Multiplication by 65,536; scales decimal fractions in the inter‐
              val [0, 1] to 16‐bit unsigned integers.

       The magnitudes of other scaling units depend on the text formatting pa‐
       rameters in effect.

       m      Em; an em is equal to the current type size in points.
       n      En; an en is one‐half em.
       v      Vee; distance between text baselines.
       M      Hundredth of an em.

   Motion quanta
       An output device’s basic unit u is not  necessarily  its  smallest  ad‐
       dressable  length;  u  can  be  smaller  to avoid problems with integer
       roundoff.  The minimum distances that a device can  work  with  in  the
       horizontal and vertical directions are termed its motion quanta, stored
       in  the .H and .V registers, respectively.  Measurements are rounded to
       applicable motion quanta.  Half‐quantum fractions round toward zero.

   Default units
       A general‐purpose register (one created or updated with the nr request;
       see section “Registers” below) is implicitly dimensionless, or reckoned
       in basic units if interpreted in a measurement context.  But it is con‐
       venient for many requests and escape sequences to infer a scaling  unit
       for  an  argument  if none is specified.  An explicit scaling unit (not
       after a closing parenthesis) can override an undesirable default.   Ef‐
       fectively,  the default unit is suffixed to the expression if a scaling
       unit is not already present.  GNU troff’s  use  of  integer  arithmetic
       should also be kept in mind; see below.

Numeric expressions
       A  numeric expression evaluates to an integer.  The following operators
       are recognized.

             +   addition
             -   subtraction
             *   multiplication
             /   truncating division
             %   modulus
       ────────────────────────────────────────────
       unary +   assertion, motion, incrementation
       unary -   negation, motion, decrementation
       ────────────────────────────────────────────
             ;   scaling
            >?   maximum
            <?   minimum
       ────────────────────────────────────────────
             <   less than
             >   greater than
            <=   less than or equal
            >=   greater than or equal
             =   equal
            ==   equal
       ────────────────────────────────────────────
             &   logical conjunction (“and”)
             :   logical disjunction (“or”)
             !   logical complementation (“not”)
       ────────────────────────────────────────────
           ( )   precedence
       ────────────────────────────────────────────
             |   boundary‐relative motion

       troff provides a set of mathematical and logical operators familiar  to
       programmers—as  well  as  some  unusual  ones—but supports only integer
       arithmetic.  (Provision is made for interpreting and reporting  decimal
       fractions in certain cases.)  The internal data type used for computing
       results is usually a 32‐bit signed integer, which suffices to represent
       magnitudes  within  a  range of ±2 billion.  (If that’s not enough, see
       groff_tmac(5) for the 62bit.tmac macro package.)

       Arithmetic infix operators perform a function on  the  numeric  expres‐
       sions  to their left and right; they are + (addition), - (subtraction),
       * (multiplication), / (truncating division), and % (modulus).  Truncat‐
       ing division rounds to the integer nearer to zero, no matter how  large
       the fractional portion.  Overflow and division (or modulus) by zero are
       errors and abort evaluation of a numeric expression.

       Arithmetic  unary  operators operate on the numeric expression to their
       right; they are - (negation) and + (assertion—for completeness; it does
       nothing).  The unary minus must often be used with parentheses to avoid
       confusion with the decrementation operator, discussed below.

       The sign of the modulus of operands of mixed signs is determined by the
       sign of the first.  Division and modulus operators satisfy the  follow‐
       ing  property:  given a dividend a and a divisor b, a quotient q formed
       by “(a / b)” and a remainder r by “(a % b)”, then qb + r = a.

       GNU troff’s scaling operator, used with parentheses as (c;e), evaluates
       a numeric expression e using c as the default scaling unit.   If  c  is
       omitted,  scaling  units are ignored in the evaluation of e.  GNU troff
       also provides a pair  of  operators  to  compute  the  extrema  of  two
       operands: >? (maximum) and <? (minimum).

       Comparison operators comprise < (less than), > (greater than), <= (less
       than  or  equal),  >=  (greater than or equal), and = (equal).  == is a
       synonym for =.  When evaluated, a comparison is replaced with “0” if it
       is false and “1” if true.  In the roff language,  positive  values  are
       true, others false.

       We  can  operate  on truth values with the logical operators & (logical
       conjunction or “and”) and : (logical disjunction or “or”).  They evalu‐
       ate as comparison operators do.  A logical complementation (“not”)  op‐
       erator,  !,  works  only within “if”, “ie”, and “while” requests.  Fur‐
       thermore, ! is recognized only at the beginning of a numeric expression
       not contained by another numeric expression.  In other words,  it  must
       be  the “outermost” operator.  Including it elsewhere in the expression
       produces a warning in the “number” category (see troff(1)), and its ex‐
       pression evaluates false.  This unfortunate limitation  maintains  com‐
       patibility  with  AT&T troff.  Test a numeric expression for falsity by
       comparing it to a false value.

       The roff language has no operator precedence: expressions are evaluated
       strictly from left to right, in  contrast  to  schoolhouse  arithmetic.
       Use parentheses ( ) to impose a desired precedence upon subexpressions.

       For  many  requests and escape sequences that cause motion on the page,
       the unary operators + and - work differently when leading a numeric ex‐
       pression.  They then indicate a motion relative to  the  drawing  posi‐
       tion: positive is down in vertical contexts, right in horizontal ones.

       +  and - are also treated differently by the following requests and es‐
       cape sequences: bp, in, ll, pl, pn, po, ps, pvs, rt, ti,  \H,  \R,  and
       \s.   Here,  leading  plus  and minus signs serve as incrementation and
       decrementation operators, respectively.  To negate an expression,  sub‐
       tract  it  from zero or include the unary minus in parentheses with its
       argument.

       A leading | operator indicates a motion relative not to the drawing po‐
       sition but to a boundary.   For  horizontal  motions,  the  measurement
       specifies  a  distance  relative to a drawing position corresponding to
       the beginning of the input line.  By default, tab  stops  reckon  move‐
       ments  in  this  way.  Most escape sequences do not; | tells them to do
       so.  For vertical motions, the | operator specifies a distance from the
       first text baseline on the page or in the current diversion, using  the
       current vertical spacing.

       The \B escape sequence tests its argument for validity as a numeric ex‐
       pression.

       A register interpolated as an operand in a numeric expression must have
       an Arabic format; luckily, this is the default.

       Due  to the way arguments are parsed, spaces are not allowed in numeric
       expressions unless the (sub)expression containing them is surrounded by
       parentheses.

Identifiers
       An identifier labels a GNU troff datum such as a register, name (macro,
       string, or diversion), typeface, color,  special  character,  character
       class,  environment,  or  stream.   Valid identifiers consist of one or
       more ordinary characters.  An ordinary character is an input  character
       that is not the escape character, a leader, tab, newline, or invalid as
       GNU troff input.

       Invalid  input  characters  are  subset of control characters (from the
       sets “C0 Controls” and “C1 Controls” as Unicode describes them).   When
       troff  encounters  one in an identifier, it produces a warning in cate‐
       gory “input” (see section “Warnings” in troff(1)).   They  are  removed
       during  interpretation:  an  identifier  “foo”,  followed by an invalid
       character and then “bar”, is processed as “foobar”.

       On a machine using the ISO 646, 8859, or 10646 character encodings, in‐
       valid input characters are 0x00, 0x08, 0x0B, 0x0D–0x1F, and  0x80–0x9F.
       On  an  EBCDIC  host,  they are 0x00–0x01, 0x08, 0x09, 0x0B, 0x0D–0x14,
       0x17–0x1F, and 0x30–0x3F.  Some of these code points are used by  troff
       internally, making it non‐trivial to extend the program to accept UTF‐8
       or other encodings that use characters from these ranges.

       An  identifier  with  a  closing bracket (“]”) in its name can’t be ac‐
       cessed with bracket‐form escape sequences that expect an identifier  as
       a  parameter.   Similarly, the identifier “(” can’t be interpolated ex‐
       cept with bracket forms.

       If you begin a macro, string, or diversion  name  with  either  of  the
       characters  “[” or “]”, you foreclose use of the refer(1) preprocessor,
       which recognizes “.[” and “.]” as bibliographic reference delimiters.

       The escape sequence \A tests its argument for validity  as  an  identi‐
       fier.

       How GNU troff handles the interpretation of an undefined identifier de‐
       pends  on the context.  There is no way to invoke an undefined request;
       such syntax is interpreted as a macro call instead.  If the  identifier
       is  interpreted as a string, macro, or diversion, troff emits a warning
       in category “mac”, defines it as empty, and interpolates  nothing.   If
       the  identifier  is interpreted as a register, troff emits a warning in
       category “reg”, initializes it to zero, and  interpolates  that  value.
       See  section “Warnings” in troff(1), and subsection “Interpolating reg‐
       isters” and section “Strings” below.  Attempting to  use  an  undefined
       typeface,  style,  special  character, color, character class, environ‐
       ment, or stream generally provokes an error diagnostic.

       Identifiers for requests, macros, strings,  and  diversions  share  one
       name space; special characters and character classes another.  No other
       object types do.

Control characters
       Control  characters  are  recognized  only at the beginning of an input
       line, or at the beginning of the branch of a control structure request;
       see section “Control structures” below.

       A few requests cause a break implicitly; use the no‐break control char‐
       acter to prevent the break.  Break suppression is its  sole  behavioral
       distinction.   Employing  the  no‐break control character to invoke re‐
       quests that don’t cause breaks is harmless but poor style.

       The control character “.” and the no‐break control character “'” can be
       changed with the cc and c2 requests, respectively.  Within a macro def‐
       inition, register .br indicates the control character used to call it.

Invoking requests
       A control character is optionally followed by tabs  and/or  spaces  and
       then an identifier naming a request or macro.  The invocation of an un‐
       recognized  request  is  interpreted as a macro call.  Defining a macro
       with the same name as a request replaces the request.  Deleting  a  re‐
       quest  name  with the rm request makes it unavailable.  The als request
       can alias requests, permitting them to be wrapped or  non‐destructively
       replaced.  See section “Strings” below.

       There  is  no  inherent limit on argument length or quantity.  Most re‐
       quests take one or more arguments, and ignore any they do  not  expect.
       A  request  may  be separated from its arguments by tabs or spaces, but
       only spaces can separate an argument from its successor.  Only one  be‐
       tween  arguments  is  necessary; any excess is ignored.  GNU troff does
       not allow tabs for argument separation.

       Generally, a space within a request argument is not relevant, not mean‐
       ingful, or is supported by bespoke provisions, as with the tl request’s
       delimiters.  Some requests, like ds, interpret  the  remainder  of  the
       control line as a single argument.  See section “Strings” below.

       Spaces  and  tabs  immediately  after  a control character are ignored.
       Commonly, authors structure the source of documents or macro files with
       them.

Calling macros
       If a macro of the desired name does not exist when called, it  is  cre‐
       ated,  assigned an empty definition, and a warning in category “mac” is
       emitted.  Calling an undefined macro does end a macro definition naming
       it as its end macro (see section “Writing macros” below).

       To embed spaces within a macro argument, enclose the argument  in  neu‐
       tral  double  quotes ‘"’.  Horizontal motion escape sequences are some‐
       times a better choice for arguments to be formatted as text.

       The foregoing raises the question of how to embed neutral double quotes
       or backslashes in macro arguments when those characters are desired  as
       literals.   In  GNU  troff, the special character escape sequence \[rs]
       produces a backslash and \[dq] a neutral double quote.

       In GNU troff’s AT&T compatibility mode, these characters remain  avail‐
       able  as  \(rs and \(dq, respectively.  AT&T troff did not consistently
       define these special characters, but its descendants  can  be  made  to
       support  them.   See  groff_font(5).  If even that is not feasible, see
       the “Calling Macros” section of the groff Texinfo manual for  the  com‐
       plex macro argument quoting rules of AT&T troff.

Using escape sequences
       Whereas  requests must occur on control lines, escape sequences can oc‐
       cur intermixed with text and  may  appear  in  arguments  to  requests,
       macros,  and  other escape sequences.  An escape sequence is introduced
       by the escape character, a backslash \.  The next character selects the
       escape’s function.

       Escape sequences vary in length.  Some take an argument, and of  those,
       some  have different syntactical forms for a one‐character, two‐charac‐
       ter, or arbitrary‐length argument.  Others accept  only  an  arbitrary‐
       length  argument.   In the former scheme, a one‐character argument fol‐
       lows the function character immediately, an opening parenthesis “(” in‐
       troduces a two‐character argument (no closing parenthesis is used), and
       an argument of arbitrary length is enclosed in brackets “[]”.   In  the
       latter  scheme,  the  user selects a delimiter character.  A few escape
       sequences are idiosyncratic, and support both of the foregoing  conven‐
       tions  (\s), designate their own termination sequence (\?), consume in‐
       put until the next newline (\!, \", \#), or support an additional modi‐
       fier character (\s again, and \n).

       If an escape character is followed by a character that does  not  iden‐
       tify  a defined operation, the escape character is ignored (producing a
       diagnostic of the “escape” warning category, which is  not  enabled  by
       default) and the following character is processed normally.

       Escape  sequence  interpolation is of higher precedence than escape se‐
       quence argument interpretation.  This rule affords flexibility in using
       escape sequences to construct parameters to other escape sequences.

       The escape character can be interpolated (\e).  Requests permit the es‐
       cape mechanism to be deactivated (eo) and restored, or the escape char‐
       acter changed (ec), and to save and restore it (ecs and ecr).

Delimiters
       Some escape sequences that require parameters use delimiters.  The neu‐
       tral apostrophe ' is a popular choice and shown in this document.   The
       neutral  double  quote " is also commonly seen.  Letters, numerals, and
       leaders can be used.  Punctuation characters are likely better choices,
       except for those defined as infix operators in numeric expressions; see
       below.

       The following escape sequences don’t take arguments and  thus  are  al‐
       lowed  as  delimiters:  \space, \%, \|, \^, \{, \}, \', \`, \-, \_, \!,
       \?, \), \/, \,, \&, \:, \~, \0, \a, \c, \d, \e, \E, \p, \r, \t, and \u.
       However, using them this way is discouraged; they can  make  the  input
       confusing to read.

       A few escape sequences, \A, \b, \o, \w, \X, and \Z, accept a newline as
       a  delimiter.   Newlines that serve as delimiters continue to be recog‐
       nized as input line terminators.  Use of newlines as delimiters in  es‐
       cape sequences is also discouraged.

       Finally,  the  escape sequences \D, \h, \H, \l, \L, \N, \R, \s, \S, \v,
       and \x prohibit many delimiters.

              • the numerals 0–9 and the decimal point “.”

              • the (single‐character) operators +-/*%<>=&:()

              • any escape sequences other than \%, \:, \{, \},  \',  \`,  \-,
                \_, \!, \/, \c, \e, and \p

       Delimiter  syntax is complex and flexible primarily for historical rea‐
       sons; the foregoing restrictions need be kept in mind mainly when using
       groff in AT&T compatibility mode.  GNU troff keeps track of the nesting
       depth of escape sequence interpolations, so  the  only  characters  you
       need  to  avoid  using as delimiters are those that appear in the argu‐
       ments you input, not any that result from interpolation.  Typically,  '
       works fine.  See section “Implementation differences” in groff_diff(7).

Dummy characters
       As  discussed  in  roff(7),  the  first  character  on an input line is
       treated specially.  Further, formatting a glyph has  many  consequences
       on  formatter  state (see section “Environments” below).  Occasionally,
       we want to escape this context or embrace some  of  those  consequences
       without  actually  rendering  a glyph to the output.  \& interpolates a
       dummy character, which is constitutive of output  but  invisible.   Its
       presence  alters the interpretation context of a subsequent input char‐
       acter, and enjoys several applications: preventing the insertion of ex‐
       tra space after an end‐of‐sentence character, preventing interpretation
       of a control character at the beginning of an  input  line,  preventing
       kerning  between  two  glyphs, and permitting the tr request to remap a
       character to “nothing”.  \) works as \& does, except that it  does  not
       cancel a pending end‐of‐sentence state.

Control structures
       groff  has  “if”  and  “while” control structures like other languages.
       However, the syntax for grouping multiple input lines in  the  branches
       or bodies of these structures is unusual.

       They  have  a  common form: the request name is (except for .el “else”)
       followed by a conditional expression cond‐expr; the  remainder  of  the
       line,  anything, is interpreted as if it were an input line.  Any quan‐
       tity of spaces between arguments to requests serves  only  to  separate
       them;  leading spaces in anything are therefore not seen.  anything ef‐
       fectively cannot be omitted; if  cond‐expr  is  true  and  anything  is
       empty,  the  newline at the end of the control line is interpreted as a
       blank line (and therefore a blank text line).

       It is frequently desirable for a control structure to govern more  than
       one  request, macro call, or text line, or a combination of the forego‐
       ing.  The opening and closing brace escape sequences \{ and \}  perform
       such  grouping.   Brace  escape sequences outside of control structures
       have no meaning and produce no output.

       \{ should appear (after optional spaces and  tabs)  immediately  subse‐
       quent  to  the request’s conditional expression.  \} should appear on a
       line with other occurrences of itself as  necessary  to  match  \{  se‐
       quences.   It can be preceded by a control character, spaces, and tabs.
       Input after any quantity of \} sequences on the same line is  processed
       only if all the preceding conditions to which they correspond are true.
       Furthermore, a \} closing the body of a .while request must be the last
       such escape sequence on an input line.

   Conditional expressions
       The  .if, .ie, and .while requests test the truth values of numeric ex‐
       pressions.  They also support several additional Boolean operators; the
       members of this expanded  class  are  termed  conditional  expressions;
       their truth values are as shown below.

       cond‐expr...   ...is true if...
       ────────────────────────────────────────────────────────────────────────
            's1's2'   s1 produces the same formatted output as s2.
                c g   a glyph g is available.
                d m   a string, macro, diversion, or request m is defined.
                  e   the current page number is even.
                F f   a font named f is available.
                m c   a color named c is defined.
                  n   the formatter is in nroff mode.
                  o   the current page number is odd.
                r n   a register named n is defined.
                S s   a font style named s is available.
                  t   the formatter is in troff mode.
                  v   n/a (historical artifact; always false).

       If  the  first argument to an .if, .ie, or .while request begins with a
       non‐alphanumeric character apart from ! (see  below);  it  performs  an
       output  comparison  test.   Shown  first in the table above, the output
       comparison operator interpolates a true value if  formatting  its  com‐
       parands  s1 and s2 produces the same output commands.  Other delimiters
       can be used in place of the neutral apostrophes.  troff formats s1  and
       s2  in  separate environments; after the comparison, the resulting data
       are discarded.  The resulting glyph properties, including font  family,
       style,  size,  and  slant, must match, but not necessarily the requests
       and/or escape sequences used to obtain them.   Motions  must  match  in
       orientation and magnitude to within the applicable horizontal or verti‐
       cal motion quantum of the device, after rounding.

       Surround  the  comparands with \? to avoid formatting them; this causes
       them to be compared character by character, as with string  comparisons
       in other programming languages.  Since comparands protected with \? are
       read  in  copy mode, they need not even be valid groff syntax.  The es‐
       cape character is still lexically recognized, however, and consumes the
       next character.

       The above operators can’t be combined with most others, but  a  leading
       “!”, not followed immediately by spaces or tabs, complements an expres‐
       sion.   Spaces  and  tabs  are optional immediately after the “c”, “d”,
       “F”, “m”, “r”, and “S” operators, but right after  “!”,  they  end  the
       predicate  and  the conditional evaluates true.  (This bizarre behavior
       maintains compatibility with AT&T troff.)

Syntax reference conventions
       In the following request and escape sequence specifications, most argu‐
       ment names were chosen to be descriptive.  A few  denotations  may  re‐
       quire introduction.

              c         denotes a single input character.
              font      a  font  either  specified as a font name or a numeric
                        mounting position.
              anything  all characters up to the end of the line, to the  end‐
                        ing  delimiter  for  the escape sequence, or within \{
                        and \}.  Escape sequences may generally be used freely
                        in anything, except when it is read in copy mode.
              message   is a character sequence to be emitted on the  standard
                        error  stream.  Special character escape sequences are
                        not interpreted.
              n         is a numeric expression that evaluates to a  non‐nega‐
                        tive integer.
              npl       is a numeric expression constituting a count of subse‐
                        quent  productive input lines; that is, those that di‐
                        rectly produce formatted output.  Text  lines  produce
                        output,  as  do control lines containing requests like
                        .tl or escape sequences like \D.  Macro calls are  not
                        themselves productive, but their interpolated contents
                        can be.
              ±N        is  a  numeric  expression with a meaning dependent on
                        its sign.

       If a numeric expression presented as ±N starts with a ‘+’ sign, an  in‐
       crement in the amount of of N is applied to the value applicable to the
       request  or escape sequence.  If it starts with a ‘-’ sign, a decrement
       of magnitude N is applied instead.  Without a sign, N replaces any  ex‐
       isting  value.   A  leading  minus sign in N is always interpreted as a
       decrementation operator, not an algebraic sign.  To assign a register a
       negative value or the negated value of  another  register,  enclose  it
       with  its  operand in parentheses or subtract it from zero.  If a prior
       value does not exist (the register  was  undefined),  an  increment  or
       decrement is applied as if to 0.

Request short reference
       Not  all  details of request behavior are outlined here.  See the groff
       Texinfo manual or, for features new to GNU troff, groff_diff(7).

       .ab       Abort processing; exit with failure status.
       .ab message
                 Abort processing; write message to the standard error  stream
                 and exit with failure status.
       .ad       Enable  output  line  alignment and adjustment using the mode
                 stored in \n[.j].
       .ad c     Enable  output  line  alignment  and  adjustment  in  mode  c
                 (c=b,c,l,n,r).  Sets \n[.j].
       .af register c
                 Assign  format  c to register, where c is “i”, “I”, “a”, “A”,
                 or a sequence of decimal digits whose  quantity  denotes  the
                 minimum  width  in digits to be used when the register is in‐
                 terpolated.  “i” and “a” indicate Roman  numerals  and  basic
                 Latin alphabetics, respectively, in the lettercase specified.
                 The default is 0.
       .aln new old
                 Create  alias  (additional  name)  new  for existing register
                 named old.
       .als new old
                 Create alias (additional  name)  new  for  existing  request,
                 string, macro, or diversion old.
       .am macro Append to macro until .. is encountered.
       .am macro end
                 Append to macro until .end is called.
       .am1 macro
                 Same  as  .am but with compatibility mode switched off during
                 macro expansion.
       .am1 macro end
                 Same as .am but with compatibility mode switched  off  during
                 macro expansion.
       .ami macro
                 Append to a macro whose name is contained in the string macro
                 until .. is encountered.
       .ami macro end
                 Append  to  a  macro  indirectly.   macro and end are strings
                 whose contents are interpolated for the macro  name  and  the
                 end macro, respectively.
       .ami1 macro
                 Same  as .ami but with compatibility mode switched off during
                 macro expansion.
       .ami1 macro end
                 Same as .ami but with compatibility mode switched off  during
                 macro expansion.
       .as name  Create  string name with empty contents; no operation if name
                 already exists.
       .as name contents
                 Append contents to string name.
       .as1 string
       .as1 string contents
                 As .as, but with compatibility mode  disabled  when  contents
                 interpolated.
       .asciify diversion
                 Unformat  ASCII characters, spaces, and some escape sequences
                 in diversion.
       .backtrace
                 Write the state of the input  stack  to  the  standard  error
                 stream.  See the -b option of groff(1).
       .bd font  Stop emboldening font font.
       .bd font n
                 Embolden font by overstriking its glyphs offset by n-1 units.
                 See register .b.
       .bd special‐font font
                 Stop emboldening special‐font when font is selected.
       .bd special‐font font n
                 Embolden  special‐font, overstriking its glyphs offset by n-1
                 units when font is selected.  See register .b.
       .blm      Unset blank line macro (trap).  Restore default  handling  of
                 blank lines.
       .blm name Set blank line macro (trap) to name.
       .box      Stop  directing output to current diversion; any pending out‐
                 put line is discarded.
       .box name Direct output to diversion name, omitting  a  partially  col‐
                 lected line.
       .boxa     Stop  appending output to current diversion; any pending out‐
                 put line is discarded.
       .boxa name
                 Append output to diversion name, omitting  a  partially  col‐
                 lected line.
       .bp       Break page and start a new one.
       .bp ±N    Break page, starting a new one numbered ±N.
       .br       Break output line.
       .brp      Break output line; adjust if applicable.
       .break    Break out of a while loop.
       .c2       Reset no‐break control character to “'”.
       .c2 o     Recognize ordinary character o as no‐break control character.
       .cc       Reset control character to ‘.’.
       .cc o     Recognize ordinary character o as the control character.
       .ce       Break,  center  the  output of the next productive input line
                 without filling, and break again.
       .ce npl   Break, center the output of the  next  npl  productive  input
                 lines  without  filling,  then break again.  If npl ≤ 0, stop
                 centering.
       .cf file  Copy contents of file without formatting to  the  (top‐level)
                 diversion.
       .cflags n c1 c2 ...
                 Assign  properties  encoded by n to characters c1, c2, and so
                 on.
       .ch name  Unplant page location trap name.
       .ch name vpos
                 Change page location trap name planted by .wh by  moving  its
                 location to vpos (default scaling unit v).
       .char c contents
                 Define ordinary or special character c as contents.
       .chop object
                 Remove  the  last character from the macro, string, or diver‐
                 sion named object.
       .class name c1 c2 ...
                 Define a (character) class name comprising the characters  or
                 range expressions c1, c2, and so on.
       .close stream
                 Close the stream.
       .color    Enable output of color‐related device‐independent output com‐
                 mands.
       .color n  If n is zero, disable output of color‐related device‐indepen‐
                 dent output commands; otherwise, enable them.
       .composite from to
                 Map  glyph  name  from  to glyph name to while constructing a
                 composite glyph name.
       .continue Finish the current iteration of a while loop.
       .cp       Enable compatibility mode.
       .cp n     If n is zero, disable compatibility  mode,  otherwise  enable
                 it.
       .cs font n m
                 Set  constant  character width mode for font to n/36 ems with
                 em m.
       .cu       Continuously underline the output of the next productive  in‐
                 put line.
       .cu npl   Continuously  underline the output of the next npl productive
                 input lines.  If npl=0, stop continuously underlining.
       .da       Stop appending output to current diversion.
       .da name  Append output to diversion name.
       .de macro Define or redefine macro until “..” occurs at the start of  a
                 control line in the current conditional block.
       .de macro end
                 Define  or  redefine  macro until end is invoked or called at
                 the start of a control line in the current conditional block.
       .de1 macro
                 As .de, but disable compatibility mode  during  macro  expan‐
                 sion.
       .de1 macro end
                 As  “.de  macro  end”,  but disable compatibility mode during
                 macro expansion.
       .defcolor ident scheme color‐component ...
                 Define a color named ident.  scheme identifies a color  space
                 and  determines  the  number of required color‐components; it
                 must be one  of  “rgb”  (three  components),  “cmy”  (three),
                 “cmyk” (four), or “gray” (one).  “grey” is accepted as a syn‐
                 onym  of  “gray”.   The  color components can be encoded as a
                 single hexadecimal value starting with # or ##.   The  former
                 indicates  that  each component is in the range 0–255 (0–FF),
                 the latter the range 0–65,535 (0–FFFF).  Alternatively,  each
                 color component can be specified as a decimal fraction in the
                 range  0–1,  interpreted using a default scaling unit of “f”,
                 which multiplies its  value  by  65,536  (but  clamps  it  at
                 65,535).   Each  output  device  has a color named “default”,
                 which cannot be redefined.  A  device’s  default  stroke  and
                 fill colors are not necessarily the same.
       .dei macro
                 Define  macro  indirectly.   As .de, but use interpolation of
                 string macro as the name of the defined macro.
       .dei macro end
                 Define macro indirectly.  As .de, but use  interpolations  of
                 strings  macro  and  end  as the names of the defined and end
                 macros.
       .dei1 macro
                 As .dei, but disable compatibility mode during  macro  expan‐
                 sion.
       .dei1 macro end
                 As  .dei  macro  end,  but  disable compatibility mode during
                 macro expansion.
       .device anything
                 Write anything, read in copy mode, to troff output as  a  de‐
                 vice  control  command.   An  initial neutral double quote is
                 stripped to allow embedding of leading spaces.
       .devicem name
                 Write contents of macro or string name to troff output  as  a
                 device control command.
       .di       Stop directing output to current diversion.
       .di name  Direct output to diversion name.
       .do name ...
                 Interpret  the  string,  request,  diversion,  or  macro name
                 (along with any arguments) with compatibility mode  disabled.
                 Compatibility  mode  is restored (only if it was active) when
                 the expansion of name is interpreted.
       .ds name  Create empty string name.
       .ds name contents
                 Create a string name containing contents.
       .ds1 name
       .ds1 name contents
                 As .ds, but with compatibility mode  disabled  when  contents
                 interpolated.
       .dt       Clear diversion trap.
       .dt vertical‐position name
                 Set  the  diversion  trap  to macro name at vertical‐position
                 (default scaling unit v).
       .ec       Recognize \ as the escape character.
       .ec o     Recognize ordinary character o as the escape character.
       .ecr      Restore escape character saved with .ecs.
       .ecs      Save the escape character.
       .el anything
                 Interpret anything as if it were an input line if the  condi‐
                 tional expression of the corresponding .ie request was false.
       .em name  Call macro name after the end of input.
       .eo       Disable the escape mechanism in interpretation mode.
       .ev       Pop environment stack, returning to previous one.
       .ev env   Push current environment onto stack and switch to env.
       .evc env  Copy environment env to the current one.
       .ex       Exit with successful status.
       .fam      Set default font family to previous value.
       .fam name Set default font family to name.
       .fc       Disable field mechanism.
       .fc a     Set field delimiter to a and pad glyph to space.
       .fc a b   Set field delimiter to a and pad glyph to b.
       .fchar c contents
                 Define fallback character (or glyph) c as contents.
       .fcolor   Restore previous fill color.
       .fcolor c Set fill color to c.
       .fi       Enable filling of output lines; a pending output line is bro‐
                 ken.  Sets \n[.u].
       .fl       Flush output buffer.
       .fp pos id
                 Mount font with font description file name id at non‐negative
                 position n.
       .fp pos id font‐description‐file‐name
                 Mount font with font‐description‐file‐name as name id at non‐
                 negative position n.
       .fschar f c anything
                 Define  fallback  character (or glyph) c for font f as string
                 anything.
       .fspecial font
                 Reset list of special fonts for font to be empty.
       .fspecial font s1 s2 ...
                 When the current font is font, then the fonts s1, s2, ... are
                 special.
       .ft
       .ft P     Select previous font mounting  position  (abstract  style  or
                 font); same as \f[] or \fP.
       .ft font  Select  typeface  font, which can be a mounting position, ab‐
                 stract style, or font name; same as \f[font] escape sequence.
                 font cannot be P.
       .ftr font1 font2
                 Translate font1 to font2.
       .fzoom font
       .fzoom font 0
                 Stop magnifying font.
       .fzoom font z
                 Set zoom factor for  font  to  z  (in  thousandths;  default:
                 1000).
       .gcolor   Restore previous stroke color.
       .gcolor c Set stroke color to c.
       .hc       Reset the hyphenation character to \% (the default).
       .hc char  Change the hyphenation character to char.
       .hcode c1 code1 [c2 code2] ...
                 Set the hyphenation code of character c1 to code1, that of c2
                 to code2, and so on.
       .hla lang Set the hyphenation language to lang.
       .hlm n    Set  the  maximum quantity of consecutive hyphenated lines to
                 n.
       .hpf pattern‐file
                 Read hyphenation patterns from pattern‐file.
       .hpfa pattern‐file
                 Append hyphenation patterns from pattern‐file.
       .hpfcode a b [c d] ...
                 Define mappings for character codes  in  hyphenation  pattern
                 files read with .hpf and .hpfa.
       .hw word ...
                 Define  hyphenation overrides for each word; a hyphen “-” in‐
                 dicates a hyphenation point.
       .hy       Set automatic hyphenation mode to 1.
       .hy 0     Disable automatic hyphenation; same as .nh.
       .hy mode  Set automatic hyphenation mode to mode; see section  “Hyphen‐
                 ation” below.
       .hym      Set the (right) hyphenation margin to 0 (the default).
       .hym length
                 Set the (right) hyphenation margin to length (default scaling
                 unit m).
       .hys      Set the hyphenation space to 0 (the default).
       .hys hyphenation‐space
                 Suppress automatic hyphenation in adjustment modes “b” or “n”
                 if  the  line can be justified with the addition of up to hy‐
                 phenation‐space to each  inter‐word  space  (default  scaling
                 unit m).
       .ie cond‐expr anything
                 If cond‐expr is true, interpret anything as if it were an in‐
                 put line, otherwise skip to a corresponding .el request.
       .if cond‐expr anything
                 If  cond‐expr  is true, then interpret anything as if it were
                 an input line.
       .ig       Ignore input (except for side effects of  \R  on  auto‐incre‐
                 menting  registers)  until “..” occurs at the start of a con‐
                 trol line in the current conditional block.
       .ig end   Ignore input (except for side effects of  \R  on  auto‐incre‐
                 menting  registers)  until  .end  is called at the start of a
                 control line in the current conditional block.
       .in       Set indentation amount to previous value.
       .in ±N    Set indentation to ±N (default scaling unit m).
       .it       Cancel any pending input line trap.
       .it npl name
                 Set (or replace) an input line trap in the environment, call‐
                 ing macro name, after the next  npl  productive  input  lines
                 have  been  read.   Lines  interrupted with the \c escape se‐
                 quence are counted separately.
       .itc      Cancel any pending input line trap.
       .itc npl name
                 As .it, except that input lines interrupted with the  \c  es‐
                 cape sequence are not counted.
       .kern     Enable pairwise kerning.
       .kern n   If n is zero, disable pairwise kerning, otherwise enable it.
       .lc       Unset leader repetition character.
       .lc c     Set leader repetition character to c (default: “.”).
       .length reg anything
                 Compute  the  number  of characters of anything and store the
                 count in the register reg.
       .linetabs Enable line‐tabs mode (calculate tab  positions  relative  to
                 beginning of output line).
       .linetabs 0
                 Disable line‐tabs mode.
       .lf n     Set number of next input line to n.
       .lf n file
                 Set  number  of  next  input line to n and input file name to
                 file.
       .lg m     Set ligature mode to m (0 = disable, 1 = enable, 2  =  enable
                 for two‐letter ligatures only).
       .ll       Set line length to previous value.  Does not affect a pending
                 output line.
       .ll ±N    Set  line  length to ±N (default length 6.5i, default scaling
                 unit m).  Does not affect a pending output line.
       .lsm      Unset the leading space macro (trap).  Restore  default  han‐
                 dling of lines with leading spaces.
       .lsm name Set the leading space macro (trap) to name.
       .ls       Change to the previous value of additional intra‐line skip.
       .ls n     Set  additional  intra‐line  skip value to n, i.e., n-1 blank
                 lines are inserted after each text output line.
       .lt       Set length of title lines to previous value.
       .lt ±N    Set length of title lines (default length 6.5i, default scal‐
                 ing unit m).
       .mc       Cease writing margin character.
       .mc c     Begin writing margin character c to the right of each  output
                 line.
       .mc c d   Begin  writing margin character c on each output line at dis‐
                 tance d to the right of the right  margin  (default  distance
                 10p, default scaling unit m).
       .mk       Mark  vertical  drawing position in an internal register; see
                 .rt.
       .mk register
                 Mark vertical drawing position in register.
       .mso file As .so, except that file is sought in the tmac directories.
       .msoquiet file
                 As .mso, but no warning is emitted if file does not exist.
       .na       Disable output line adjustment.
       .ne       Break page if distance to next page  location  trap  is  less
                 than one vee.
       .ne d     Break  page  if  distance  to next page location trap is less
                 than distance d (default scaling unit v).
       .nf       Disable filling of output lines; a  pending  output  line  is
                 broken.  Clears \n[.u].
       .nh       Disable automatic hyphenation; same as “.hy 0”.
       .nm       Deactivate output line numbering.
       .nm ±N
       .nm ±N m
       .nm ±N m s
       .nm ±N m s i
                 Activate  output  line numbering: number the next output line
                 ±N, writing numbers every m lines, with s numeral widths (\0)
                 between the line number and the output (default 1),  and  in‐
                 denting the line number by i numeral widths (default 0).
       .nn       Suppress  numbering  of  the  next output line to be numbered
                 with nm.
       .nn n     Suppress numbering of the next n output lines to be  numbered
                 with nm.  If n=0, cancel suppression.
       .nop anything
                 Interpret anything as if it were an input line.
       .nr reg ±N
                 Define or update register reg with value N.
       .nr reg ±N I
                 Define or update register reg with value N and auto‐increment
                 I.
       .nroff    Make the conditional expressions n true and t false.
       .ns       Enable  no‐space mode, ignoring .sp requests until a glyph or
                 \D primitive is output.  See .rs.
       .nx       Immediately jump to end of current file.
       .nx file  Stop formatting current file and begin reading file.
       .open stream file
                 Open file for writing and associate the stream  named  stream
                 with it.  Unsafe request; disabled by default.
       .opena stream file
                 As  .open,  but  append to file.  Unsafe request; disabled by
                 default.
       .os       Output vertical distance that was saved by the .sv request.
       .output contents
                 Emit contents directly to intermediate output, allowing lead‐
                 ing whitespace if string starts with  "  (which  is  stripped
                 off).
       .pc       Reset page number character to ‘%’.
       .pc c     Page number character.
       .pev      Report  the state of the current environment followed by that
                 of all other environments to the standard error stream.
       .pi program
                 Pipe output to program (nroff only).   Unsafe  request;  dis‐
                 abled by default.
       .pl       Set  page  length to default 11i.  The current page length is
                 stored in register .p.
       .pl ±N    Change page length to ±N (default scaling unit v).
       .pm       Report, to the standard error stream, the names and sizes  in
                 bytes of defined macros, strings, and diversions.
       .pn ±N    Next page number N.
       .pnr      Write  the names and contents of all defined registers to the
                 standard error stream.
       .po       Change to previous page offset.  The current page  offset  is
                 available in register .o.
       .po ±N    Page offset N.
       .ps       Return to previous type size.
       .ps ±N    Set/increase/decrease  the type size to/by N scaled points (a
                 non‐positive resulting type size is set to  1  u);  also  see
                 \s[±N].
       .psbb file
                 Retrieve  the  bounding  box of the PostScript image found in
                 file, which must conform to Adobe’s Document Structuring Con‐
                 ventions (DSC).  See registers llx, lly, urx, ury.
       .pso command‐line
                 Execute command‐line with popen(3) and interpolate  its  out‐
                 put.  Unsafe request; disabled by default.
       .ptr      Report  names and positions of all page location traps to the
                 standard error stream.
       .pvs      Change to previous post‐vertical line spacing.
       .pvs ±N   Change post‐vertical line spacing according  to  ±N  (default
                 scaling unit p).
       .rchar c1 c2 ...
                 Remove  definition  of each ordinary or special character c1,
                 c2, ... defined by a .char, .fchar, or .schar request.
       .rd prompt
                 Read insertion.
       .return   Return from a macro.
       .return anything
                 Return twice, namely from the macro at the current level  and
                 from the macro one level higher.
       .rfschar f c1 c2 ...
                 Remove  the  font‐specific  definitions of glyphs c1, c2, ...
                 for font f.
       .rj npl   Break, right‐align the output of the  next  productive  input
                 line without filling, then break again.
       .rj npl   Break,  right‐align the output of the next npl productive in‐
                 put lines without filling, then break again.   If  npl  ≤  0,
                 stop right‐aligning.
       .rm name  Remove request, macro, diversion, or string name.
       .rn old new
                 Rename request, macro, diversion, or string old to new.
       .rnn reg1 reg2
                 Rename register reg1 to reg2.
       .rr ident Remove register ident.
       .rs       Restore spacing; disable no‐space mode.  See .ns.
       .rt       Return  (upward  only)  to vertical position marked by .mk on
                 the current page.
       .rt N     Return (upward only) to vertical position N (default  scaling
                 unit v).
       .schar c contents
                 Define global fallback character (or glyph) c as contents.
       .shc      Reset the soft hyphen character to \[hy].
       .shc c    Set the soft hyphen character to c.
       .shift n  In a macro definition, left‐shift arguments by n positions.
       .sizes s1 s2 ... sn [0]
                 Set  available type sizes similarly to the sizes directive in
                 a DESC file.  Each si  is  interpreted  in  units  of  scaled
                 points (z).
       .so file  Replace the request’s control line with the contents of file,
                 “sourcing” it.
       .soquiet file
                 As .so, but no warning is emitted if file does not exist.
       .sp       Break and move the next text baseline down by one vee, or un‐
                 til springing a page location trap.
       .sp dist  Break  and move the next text baseline down by dist, or until
                 springing a page location trap (default scaling unit  v).   A
                 negative  dist will not reduce the position of the text base‐
                 line below zero.  Prefixing dist with the | operator moves to
                 a position relative to the page top for positive N,  and  the
                 bottom  if N is negative; in all cases, one line height (vee)
                 is added to dist.  dist is ignored inside a diversion.
       .special  Reset global list of special fonts to be empty.
       .special s1 s2 ...
                 Fonts s1, s2, etc. are special and are  searched  for  glyphs
                 not in the current font.
       .spreadwarn
                 Toggle  the  spread  warning on and off (the default) without
                 changing its value.
       .spreadwarn N
                 Emit a break warning if the  additional  space  inserted  for
                 each  space  between  words  in  an  adjusted  output line is
                 greater than or equal to N.  A negative N is  treated  as  0.
                 The  default  scaling  unit is m.  At startup, .spreadwarn is
                 inactive and N is 3 m.
       .ss n     Set minimal inter‐word spacing to n 12ths of  current  font’s
                 space width.
       .ss n m   As  “.ss  n”,  and  set  additional  inter‐sentence  space to
                 m 12ths of current font’s space width.
       .stringdown stringvar
                 Replace each byte in the string named stringvar with its low‐
                 ercase version.
       .stringup stringvar
                 Replace each byte in the string named stringvar with its  up‐
                 percase version.
       .sty n style
                 Associate abstract style with font position n.
       .substring str start [end]
                 Replace  the  string  named str with its substring bounded by
                 the indices start and end, inclusive.  Negative indices count
                 backwards from the end of the string.
       .sv       As .ne, but save 1 v for output with .os request.
       .sv d     As .ne, but save distance d for later output with .os request
                 (default scaling unit v).
       .sy command‐line
                 Execute command‐line with system(3).   Unsafe  request;  dis‐
                 abled by default.
       .ta n1 n2 ... nn T r1 r2 ... rn
                 Set  tabs  at  positions  n1,  n2,  ..., nn, then set tabs at
                 nn+m×rn+r1 through nn+m×rn+rn, where m increments from 0,  1,
                 2,  ...  to  the  output line length.  Each n argument can be
                 prefixed with a “+” to place the tab stop ni  at  a  distance
                 relative to the previous, n(i-1).  Each argument ni or ri can
                 be suffixed with a letter to align text within the tab column
                 bounded by tab stops i and i+1; “L” for left‐aligned (the de‐
                 fault), “C” for centered, and “R” for right‐aligned.
       .tag
       .taga     Reserved for internal use.
       .tc       Unset tab repetition character.
       .tc c     Set tab repetition character to c (default: none).
       .ti ±N    Temporarily indent next output line (default scaling unit m).
       .tkf font s1 n1 s2 n2
                 Enable track kerning for font.
       .tl 'left'center'right'
                 Format three‐part title.
       .tm message
                 Write  message,  followed by a newline, to the standard error
                 stream.
       .tm1 message
                 As .tm, but an initial neutral double quote in message is re‐
                 moved, allowing it to contain leading spaces.
       .tmc message
                 As .tm1, without emitting a newline.
       .tr abcd...
                 Translate ordinary or special characters a to b, c to d,  and
                 so on prior to output.
       .trf file Transparently  output  the contents of file.  Unlike .cf, in‐
                 valid input characters in file are rejected.
       .trin abcd...
                 As .tr, except that .asciify ignores the translation  when  a
                 diversion is interpolated.
       .trnt abcd...
                 As  .tr, except that translations are suppressed in the argu‐
                 ment to \!.
       .troff    Make the conditional expressions t true and n false.
       .uf font  Set underline font used by .ul to font.
       .ul       Underline (italicize in troff mode) the output  of  the  next
                 productive input line.
       .ul npl   Underline  (italicize  in  troff mode) the output of the next
                 npl productive input line.  If npl=0, stop underlining.
       .unformat diversion
                 Unformat space characters and tabs in  diversion,  preserving
                 font information.
       .vpt      Enable vertical position traps.
       .vpt 0    Disable vertical position traps.
       .vs       Change to previous vertical spacing.
       .vs ±N    Set vertical spacing to ±N (default scaling unit p).
       .warn     Enable all warning categories.
       .warn 0   Disable all warning categories.
       .warn n   Enable  warnings  in  categories  whose  codes  sum to n; see
                 troff(1).
       .warnscale su
                 Set scaling unit used in certain warnings to su (one of u, i,
                 c, p, or P; default: i).
       .wh vpos  Remove visible page location trap at  vpos  (default  scaling
                 unit v).
       .wh vpos name
                 Plant macro name as page location trap at vpos (default scal‐
                 ing unit v), removing any visible trap already there.
       .while cond‐expr anything
                 Repeatedly execute anything unless and until cond‐expr evalu‐
                 ates false.
       .write stream anything
                 Write anything to the stream named stream.
       .writec stream anything
                 Similar to .write without emitting a final newline.
       .writem stream xx
                 Write  contents  of  macro  or  string xx to the stream named
                 stream.

Escape sequence short reference
       The escape sequences \", \#, \$, \*, \?, \a, \e, \n, \t,  \g,  \V,  and
       \newline are interpreted even in copy mode.

       \"     Comment.  Everything up to the end of the line is ignored.
       \#     Comment.  Everything up to and including the next newline is ig‐
              nored.
       \*s    Interpolate string with one‐character name s.
       \*(st  Interpolate string with two‐character name st.
       \*[string]
              Interpolate string with name string (of arbitrary length).
       \*[string arg ...]
              Interpolate  string with name string (of arbitrary length), tak‐
              ing arg ... as arguments.
       \$0    Interpolate name by which currently executing macro was invoked.
       \$n    Interpolate macro or string parameter numbered n (1≤n≤9).
       \$(nn  Interpolate macro or string parameter numbered nn (01≤nn≤99).
       \$[nnn]
              Interpolate macro or string parameter numbered nnn (nnn≥1).
       \$*    Interpolate concatenation of all  macro  or  string  parameters,
              separated by spaces.
       \$@    Interpolate  concatenation  of  all  macro or string parameters,
              with each surrounded by double quotes and separated by spaces.
       \$^    Interpolate concatenation of all macro or string  parameters  as
              if they were arguments to the .ds request.
       \'     is a synonym for \[aa], the acute accent special character.
       \`     is a synonym for \[ga], the grave accent special character.
       \-     is a synonym for \[-], the minus sign special character.
       \_     is a synonym for \[ul], the underrule special character.
       \%     Control hyphenation.
       \!     Transparent  line.   The  remainder  of the input line is inter‐
              preted (1) when the current diversion is read; or (2) if in  the
              top‐level diversion, by the postprocessor (if any).
       \?anything\?
              Transparently embed anything, read in copy mode, in a diversion,
              or  unformatted  as an output comparand in a conditional expres‐
              sion.
       \space Move right one word space.
       \~     Insert an unbreakable, adjustable space.
       \0     Move right by the width of a numeral in the current font.
       \|     Move one‐sixth em to the right on typesetters.
       \^     Move one‐twelfth em to the right on typesetters.
       \&     Interpolate a dummy character.
       \)     Interpolate a dummy character that is transparent to end‐of‐sen‐
              tence recognition.
       \/     Apply italic correction.  Use between  an  immediately  adjacent
              oblique glyph on the left and an upright glyph on the right.
       \,     Apply  left italic correction.  Use between an immediately adja‐
              cent upright glyph on the left  and  an  oblique  glyph  on  the
              right.
       \:     Non‐printing  break  point  (similar to \%, but never produces a
              hyphen glyph).
       \newline
              Continue current input line on the next.
       \{     Begin conditional input.
       \}     End conditional input.
       \(gl   Interpolate glyph with two‐character name gl.
       \[glyph]
              Interpolate glyph with name glyph (of arbitrary length).
       \[base‐char comp ...]
              Interpolate composite glyph constructed from base‐char and  each
              component comp.
       \[charnnn]
              Interpolate  glyph  of  eight‐bit  encoded  character nnn, where
              0≤nnn≤255.
       \[unnnn[n[n]]]
              Interpolate  glyph  of  Unicode  character   with   code   point
              nnnn[n[n]] in uppercase hexadecimal.
       \[ubase‐char[_combining‐component]...]
              Interpolate composite glyph from Unicode character base‐char and
              combining‐components.
       \a     Interpolate a leader in copy mode.
       \A'anything'
              Interpolate  1  if  anything is a valid identifier, and 0 other‐
              wise.
       \b'string'
              Build bracket: pile a sequence of glyphs corresponding  to  each
              character  in string vertically, and center it vertically on the
              output line.
       \B'anything'
              Interpolate 1 if anything is a valid numeric expression,  and  0
              otherwise.
       \c     Continue output line at next input line.
       \C'glyph'
              As \[glyph], but compatible with other troff implementations.
       \d     Move downward ½ em on typesetters.
       \D'drawing‐command'
              See subsection “Drawing commands” below.
       \e     Interpolate the escape character.
       \E     As \e, but not interpreted in copy mode.
       \fP    Select previous font mounting position (abstract style or font);
              same as “.ft” or “.ft P”.
       \fF    Select font mounting position, abstract style, or font with one‐
              character name or one‐digit position F.  F cannot be P.
       \f(ft  Select font mounting position, abstract style, or font with two‐
              character name or two‐digit position ft.
       \f[font]
              Select  font mounting position, abstract style, or font with ar‐
              bitrarily long name or position font.  font cannot be P.
       \f[]   Select previous font mounting position (abstract style or font).
       \Ff    Set default font family to that with one‐character name f.
       \F(fm  Set default font family to that with two‐character name fm.
       \F[fam]
              Set default font family to that with arbitrarily long name fam.
       \F[]   Set default font family to previous value.
       \gr    Interpolate format of register with one‐character name r.
       \g(rg  Interpolate format of register with two‐character name rg.
       \g[reg]
              Interpolate format of register with arbitrarily long name reg.
       \h'N'  Horizontally move the drawing position by N  ems  (or  specified
              units); | may be used.  Positive motion is rightward.
       \H'N'  Set  height  of  current  font  to N scaled points (or specified
              units).
       \kr    Mark horizontal position in one‐character register name r.
       \k(rg  Mark horizontal position in two‐character register name rg.
       \k[reg]
              Mark horizontal  position  in  register  with  arbitrarily  long
              name reg.
       \l'N[c]'
              Draw  horizontal  line  of  length  N with character c (default:
              \[ru]; default scaling unit m).
       \L'N[c]'
              Draw vertical line of length N with character c (default: \[br];
              default scaling unit v).
       \mc    Set stroke color to that with one‐character name c.
       \m(cl  Set stroke color to that with two‐character name cl.
       \m[color]
              Set stroke color to that with arbitrarily long name color.
       \m[]   Restore previous stroke color.
       \Mc    Set fill color to that with one‐character name c.
       \M(cl  Set fill color to that with two‐character name cl.
       \M[color]
              Set fill color to that with arbitrarily long name color.
       \M[]   Restore previous fill color.
       \nr    Interpolate contents of register with one‐character name r.
       \n(rg  Interpolate contents of register with two‐character name rg.
       \n[reg]
              Interpolate contents of register with arbitrarily long name reg.
       \N'n'  Interpolate glyph with index n in the current font.
       \o'abc...'
              Overstrike centered glyphs of characters a, b, c, and so on.
       \O0    At the outermost suppression level, disable emission  of  glyphs
              and geometric objects to the output driver.
       \O1    At  the  outermost  suppression level, enable emission of glyphs
              and geometric objects to the output driver.
       \O2    At the outermost suppression level, enable glyph  and  geometric
              primitive  emission  to the output driver and write to the stan‐
              dard error stream the page number, four bounding  box  registers
              enclosing  glyphs written since the previous \O escape sequence,
              the page offset, line length, image file name (if any), horizon‐
              tal and vertical device motion quanta, and input file name.
       \O3    Begin a nested suppression level.
       \O4    End a nested suppression level.
       \O[5Pfile]
              At the outermost suppression level, write the name file  to  the
              standard  error stream at position P, which must be one of l, r,
              c, or i.
       \p     Break output line at next word boundary; adjust if applicable.
       \r     Move “in reverse” (upward) 1 em.
       \R'name ±N'
              Set, increment, or decrement register name by N.
       \s±N   Set/increase/decrease the type size to/by N  scaled  points.   N
              must  be a single digit; 0 restores the previous type size.  (In
              compatibility mode only, a non‐zero  N  must  be  in  the  range
              4–39.)  Otherwise, as .ps request.
       \s(±N
       \s±(N  Set/increase/decrease  the type size to/by N scaled points; N is
              a two‐digit number ≥1.  As .ps request.
       \s[±N]
       \s±[N]
       \s'±N'
       \s±'N' Set/increase/decrease the type size to/by N scaled  points.   As
              .ps request.
       \S'N'  Slant  output glyphs by N degrees; the direction of text flow is
              positive.
       \t     Interpolate a tab in copy mode.
       \u     Move upward ½ em on typesetters.
       \v'N'  Vertically move the drawing position by  N  vees  (or  specified
              units); | may be used.  Positive motion is downward.
       \Ve    Interpolate  contents of environment variable with one‐character
              name e.
       \V(ev  Interpolate contents of environment variable with  two‐character
              name ev.
       \V[env]
              Interpolate  contents  of  environment variable with arbitrarily
              long name env.
       \w'anything'
              Interpolate width of anything, formatted in a dummy environment.
       \x'N'  Increase vertical spacing of pending output line by N  vees  (or
              specified units; negative before, positive after).
       \X'anything'
              Write  anything  to  troff  output  as a device control command.
              Within anything, the escape sequences \&, \), \%, and \: are ig‐
              nored; \space and \~ are converted to single  space  characters;
              and  \\  has  its  escape character stripped.  So that the basic
              Latin subset of the Unicode character set can  be  reliably  en‐
              coded  in  anything,  the special character escape sequences \-,
              \[aq], \[dq], \[ga], \[ha], \[rs], and \[ti] are mapped to basic
              Latin characters; see groff_char(7).  For  this  transformation,
              character translations and special character definitions are ig‐
              nored.
       \Yn    Write  contents of macro or string n to troff output as a device
              control command.
       \Y(nm  Write contents of macro or string nm to troff output as a device
              control command.
       \Y[name]
              Write contents of macro or string name to troff output as a  de‐
              vice control command.
       \zc    Format character c with zero width—without advancing the drawing
              position.
       \Z'anything'
              Save the drawing position, format anything, then restore it.

   Drawing commands
       Drawing commands direct the output device to render geometrical objects
       rather than glyphs.  Specific devices may support only a subset, or may
       feature  additional ones; consult the man page for the output driver in
       use.  Terminal devices in particular implement almost none.

       Rendering starts at the drawing position; when  finished,  the  drawing
       position  is left at the rightmost point of the object, even for closed
       figures, except where noted.  GNU troff draws  stroked  (outlined)  ob‐
       jects  with  the  stroke  color,  and  shades filled ones with the fill
       color.  See section “Colors” above.  Coordinates h and v are horizontal
       and vertical motions relative to the drawing position or previous point
       in the command.  The default scaling unit for  horizontal  measurements
       (and diameters of circles) is m; for vertical ones, v.

       Circles,  ellipses, and polygons can be drawn stroked or filled.  These
       are independent properties; if you want a filled, stroked  figure,  you
       must  draw  the same figure twice using each drawing command.  A filled
       figure is always smaller than an outlined one  because  the  former  is
       drawn  only within its defined area, whereas strokes have a line thick‐
       ness (set with \D't').

       \D'~ h1 v1 ... hn vn'
              Draw B‐spline to each point in sequence, leaving  drawing  posi‐
              tion at (hn, vn).
       \D'a hc vc h v'
              Draw circular arc centered at (hc, vc) counterclockwise from the
              drawing  position  to  a  point  (h,  v) relative to the center.
              (hc, vc) is adjusted to the point nearest the perpendicular  bi‐
              sector of the arc’s chord.
       \D'c d'
              Draw circle of diameter d with its leftmost point at the drawing
              position.
       \D'C d'
              As \D'C', but the circle is filled.
       \D'e h v'
              Draw  ellipse of width h and height v with its leftmost point at
              the drawing position.
       \D'E h v'
              As \D'e', but the ellipse is filled.
       \D'l h v'
              Draw line from the drawing position to (h, v).
       \D'p h1 v1 ... hn vn'
              Draw polygon with vertices at drawing position and each point in
              sequence.  GNU troff closes the polygon by drawing a  line  from
              (hn,  vn)  back to the initial drawing position.  Afterward, the
              drawing position is left at (hn, vn).
       \D'P h1 v1 ... hn vn'
              As \D'p', but the polygon is filled.
       \D't n'
              Set stroke thickness of geometric objects to to n  basic  units.
              A  zero n selects the minimal supported thickness.  A negative n
              selects a thickness proportional to the type size; this  is  the
              default.

   Device control commands
       The  .device and .devicem requests, and \X and \Y escape sequences, en‐
       able documents to pass information directly to a postprocessor.   These
       are  useful  for exercising device‐specific capabilities that the groff
       language does not abstract or generalize; such  functions  include  the
       embedding of hyperlinks and image files.  Device‐specific functions are
       documented in each output driver’s man page.

Strings
       groff supports strings primarily for user convenience.  Conventionally,
       if one would define a macro only to interpolate a small amount of text,
       without  invoking  requests  or calling any other macros, one defines a
       string instead.  Only one string is predefined by the language.

       \*[.T]    Contains the name of the output device (for  example,  “utf8”
                 or “pdf”).

       The  .ds  request  creates a string with a specified name and contents.
       If the identifier named by .ds already exists as an alias,  the  target
       of  the  alias  is redefined.  If .ds is called with only one argument,
       the named string becomes empty.  Otherwise, troff stores the  remainder
       of the control line in copy mode; see subsection “Copy mode” below.

       The  \* escape sequence dereferences a string’s name, interpolating its
       contents.  If the name does not exist, it is defined as empty,  nothing
       is  interpolated, and a warning in category “mac” is emitted.  See sec‐
       tion “Warnings” in troff(1).  The bracketed interpolation form  accepts
       arguments that are handled as macro arguments are; see section “Calling
       macros”  above.   In  contrast  to  macro  calls, however, if a closing
       bracket ] occurs in a string argument, that argument must  be  enclosed
       in  double quotes.  \* is interpreted even in copy mode.  When defining
       strings, argument interpolations must be escaped if they are to  refer‐
       ence  parameters from the calling context; see section “Parameters” be‐
       low.

       An initial neutral double quote " in the string contents is stripped to
       allow embedding of leading spaces.  Any other " is  interpreted  liter‐
       ally, but it is wise to use the special character escape sequence \[dq]
       instead  if  the  string might be interpolated as part of a macro argu‐
       ment; see section “Calling macros” above.  Strings are not limited to a
       single input line of text.  \newline works just as it  does  elsewhere.
       The resulting string is stored without the newlines.  Care is therefore
       required  when  interpolating strings while filling is disabled.  It is
       not possible to embed a newline in a string that will be interpreted as
       such when the string is interpolated.  To achieve that effect,  use  \*
       to interpolate a macro instead.

       The  .as  request  is similar to .ds but appends to a string instead of
       redefining it.  If .as is called with only one argument,  no  operation
       is performed (beyond dereferencing the string).

       Because  strings are similar to macros, they too can be defined to sup‐
       press AT&T troff compatibility mode enablement when  interpolated;  see
       section  “Compatibility mode” below.  The .ds1 request defines a string
       that suspends compatibility mode when the string is later interpolated.
       .as1 is likewise similar to .as, with compatibility mode suspended when
       the appended portion of the string is later interpolated.

       Caution: Unlike other requests, the second argument to  these  requests
       consumes  the  remainder  of the input line, including trailing spaces.
       Ending string definitions (and appendments) with  a  comment,  even  an
       empty  one,  prevents  unwanted  space  from  creeping into them during
       source document maintenance.

       Several  requests  exist  to  perform  rudimentary  string  operations.
       Strings  can  be  queried  (.length)  and  modified (.chop, .substring,
       .stringup, .stringdown), and their names can be manipulated through re‐
       naming, removal, and aliasing (.rn, .rm, .als).

       When a request, macro, string, or diversion is  aliased,  redefinitions
       and  appendments “write through” alias names.  To replace an alias with
       a separately defined object, you must use the rm request  on  its  name
       first.

Registers
       In  the roff language, numbers can be stored in registers.  Many built‐
       in registers exist, supplying anything from the date to details of for‐
       matting parameters.  You can also define your own.  See section  “Iden‐
       tifiers”  above for information on constructing a valid name for a reg‐
       ister.

       Define registers and update their values with the nr request or the  \R
       escape sequence.

       Registers can also be incremented or decremented by a configured amount
       at the time they are interpolated.  The value of the increment is spec‐
       ified  with a third argument to the .nr request, and a special interpo‐
       lation syntax, \n± is used to alter and then  retrieve  the  register’s
       value.   Together,  these features are called auto‐increment.  (A nega‐
       tive auto‐increment can be considered an “auto‐decrement”.)

       Many predefined registers are available.  In  the  following  presenta‐
       tion,  the register interpolation syntax \n[name] is used to refer to a
       register name to clearly distinguish it from a string or request  name.
       The  register  name  space  is  separate  from  that used for requests,
       macros, strings, and diversions.  Bear in mind that  the  symbols  \n[]
       are not part of the register name.

   Read‐only registers
       Predefined  registers whose identifiers start with a dot are read‐only.
       Many are Boolean‐valued.  Some are string‐valued, meaning that they in‐
       terpolate text.  A register name (without the dot) is often  associated
       with a request of the same name; exceptions are noted.

       \n[.$]         Count  of  arguments  passed  to  currently interpolated
                      macro or string.
       \n[.a]         Amount of extra post‐vertical line space; see \x.
       \n[.A]         Approximate output is being formatted  (Boolean‐valued);
                      see troff -a option.
       \n[.b]         Font emboldening offset; see .bd.
       \n[.br]        The  normal  control character was used to call the cur‐
                      rently interpolated macro (Boolean‐valued).
       \n[.c]         Input line number; see .lf and register “c.”.
       \n[.C]         Compatibility mode is enabled (Boolean‐valued); see .cp.
                      Always false when processing .do; see register .cp.
       \n[.cdp]       Depth of last glyph formatted in the environment;  posi‐
                      tive if glyph extends below the baseline.
       \n[.ce]        Count of output lines remaining to be centered.
       \n[.cht]       Height of last glyph formatted in the environment; posi‐
                      tive if glyph extends above the baseline.
       \n[.color]     Color output is enabled (Boolean‐valued).
       \n[.cp]        Within  .do,  the saved value of compatibility mode; see
                      register .C.
       \n[.csk]       Skew of the last glyph  formatted  in  the  environment;
                      skew  is  how  far to the right of the center of a glyph
                      the center of  an  accent  over  that  glyph  should  be
                      placed.
       \n[.d]         Vertical drawing position in diversion.
       \n[.ev]        Name of environment (string‐valued).
       \n[.f]         Mounting position of selected font; see .ft and \f.
       \n[.F]         Name of input file (string‐valued); see .lf.
       \n[.fam]       Name of default font family (string‐valued).
       \n[.fn]        Resolved  name of selected font (string‐valued); see .ft
                      and \f.
       \n[.fp]        Next non‐zero free font mounting position index.
       \n[.g]         Always true in GNU troff (Boolean‐valued).
       \n[.h]         Text baseline high‐water mark on page or in diversion.
       \n[.H]         Horizontal motion quantum  of  output  device  in  basic
                      units.
       \n[.height]    Font height; see \H.
       \n[.hla]       Hyphenation language in environment (string‐valued).
       \n[.hlc]       Count  of  immediately  preceding consecutive hyphenated
                      lines in environment.
       \n[.hlm]       Maximum quantity of consecutive hyphenated lines allowed
                      in environment.
       \n[.hy]        Automatic hyphenation mode in environment.
       \n[.hym]       Hyphenation margin in environment.
       \n[.hys]       Hyphenation space adjustment threshold in environment.
       \n[.i]         Indentation amount; see .in.
       \n[.in]        Indentation amount  applicable  to  the  pending  output
                      line; see .ti.
       \n[.int]       Previous output line was “interrupted” or continued with
                      \c (Boolean‐valued).
       \n[.j]         Adjustment  mode encoded as an integer; see .ad and .na.
                      Do not interpret or perform arithmetic on its value.
       \n[.k]         Horizontal drawing position relative to indentation.
       \n[.kern]      Pairwise kerning is enabled (Boolean‐valued).
       \n[.l]         Line length; see .ll.
       \n[.L]         Line spacing; see .ls.
       \n[.lg]        Ligature mode.
       \n[.linetabs]  Line‐tabs mode is enabled (Boolean‐valued).
       \n[.ll]        Line length applicable to the pending output line.
       \n[.lt]        Title length.
       \n[.m]         Stroke color (string‐valued); see .gcolor and \m.  Empty
                      if the stroke color is the default.
       \n[.M]         Fill color (string‐valued); see .fcolor and  \M.   Empty
                      if the fill color is the default.
       \n[.n]         Length of formatted output on previous output line.
       \n[.ne]        Amount  of  vertical  space  required  by  last .ne that
                      caused a trap to be sprung; also see register .trunc.
       \n[.nm]        Output line numbering is enabled (Boolean‐valued).
       \n[.nn]        Count of output lines remaining to have  numbering  sup‐
                      pressed.
       \n[.ns]        No‐space mode is enabled (Boolean‐valued).
       \n[.o]         Page offset; see .po.
       \n[.O]         Output suppression nesting level; see \O.
       \n[.p]         Page length; see .pl.
       \n[.P]         The  page  is  selected for output (Boolean‐valued); see
                      troff -o option.
       \n[.pe]        Page ejection is in progress (Boolean‐valued).
       \n[.pn]        Number of the next page.
       \n[.ps]        Type size in scaled points.
       \n[.psr]       Most recently requested type size in scaled points;  see
                      .ps and \s.
       \n[.pvs]       Post‐vertical line spacing.
       \n[.R]         Count  of  available  unused registers; always 10,000 in
                      GNU troff.
       \n[.rj]        Count of lines remaining to be right‐aligned.
       \n[.s]         Type size in points as a decimal  fraction  (string‐val‐
                      ued); see .ps and \s.
       \n[.slant]     Slant of font in degrees; see \S.
       \n[.sr]        Most recently requested type size in points as a decimal
                      fraction (string‐valued); see .ps and \s.
       \n[.ss]        Size  of  minimal  inter‐word  space  in twelfths of the
                      space width of the selected font.
       \n[.sss]       Size of additional inter‐sentence space in  twelfths  of
                      the space width of the selected font.
       \n[.sty]       Selected abstract style (string‐valued); see .ft and \f.
       \n[.t]         Distance  to  next  vertical  position trap; see .wh and
                      .ch.
       \n[.T]         An output device was explicitly  selected  (Boolean‐val‐
                      ued); see troff -T option.
       \n[.tabs]      Representation of tab settings suitable for use as argu‐
                      ment to .ta (string‐valued).
       \n[.trunc]     Amount  of vertical space truncated by the most recently
                      sprung vertical position  trap,  or,  if  the  trap  was
                      sprung  by  an  .ne, minus the amount of vertical motion
                      produced by .ne; also see register .ne.
       \n[.u]         Filling is enabled (Boolean‐valued); see .fi and .nf.
       \n[.U]         Unsafe mode is enabled (Boolean‐valued);  see  troff  -U
                      option.
       \n[.v]         Vertical line spacing; see .vs.
       \n[.V]         Vertical  motion  quantum  of the output device in basic
                      units.
       \n[.vpt]       Vertical position traps are enabled (Boolean‐valued).
       \n[.w]         Width of previous glyph formatted in the environment.
       \n[.warn]      Sum of the numeric codes of enabled warning categories.
       \n[.x]         Major version number of the running troff formatter.
       \n[.y]         Minor version number of the running troff formatter.
       \n[.Y]         Revision number of the running troff formatter.
       \n[.z]         Name of diversion (string‐valued).  Empty if  output  is
                      directed to the top‐level diversion.
       \n[.zoom]      Zoom multiplier of current font (in thousandths; zero if
                      no magnification); see .fzoom.

   Writable predefined registers
       Several  registers are predefined but also modifiable; some are updated
       upon interpretation of certain requests or escape sequences.  Date‐ and
       time‐related registers are set to  the  local  time  as  determined  by
       localtime(3)  when  the formatter launches.  This initialization can be
       overridden by SOURCE_DATE_EPOCH and TZ; see  section  “Environment”  of
       groff(1).

       \n[$$]         Process ID of troff.
       \n[%]          Page number.
       \n[c.]         Input line number.
       \n[ct]         Union  of  character  types  of each glyph rendered into
                      dummy environment by \w.
       \n[dl]         Width of last closed diversion.
       \n[dn]         Height of last closed diversion.
       \n[dw]         Day of the week (1–7; 1 is Sunday).
       \n[dy]         Day of the month (1–31).
       \n[hours]      Count of hours elapsed since midnight (0–23).
       \n[hp]         Horizontal drawing position relative to start  of  input
                      line.
       \n[llx]        Lower‐left  x  coordinate (in PostScript units) of Post‐
                      Script image; see .psbb.
       \n[lly]        Lower‐left y coordinate (in PostScript units)  of  Post‐
                      Script image; see .psbb.
       \n[ln]         Output line number; see .nm.
       \n[lsn]        Count of leading spaces on input line.
       \n[lss]        Amount  of  horizontal  space  corresponding  to leading
                      spaces on input line.
       \n[minutes]    Count of minutes elapsed in the hour (0–59).
       \n[mo]         Month of the year (1–12).
       \n[nl]         Vertical drawing position.
       \n[opmaxx]
       \n[opmaxy]
       \n[opminx]
       \n[opminy]     These four registers  mark  the  top  left‐  and  bottom
                      right‐hand  corners of a rectangle encompassing all for‐
                      matted output on the page.  They are reset to -1 by  \O0
                      or \O1.
       \n[rsb]        As  register sb, adding maximum glyph height to measure‐
                      ment.
       \n[rst]        As register st, adding maximum glyph depth  to  measure‐
                      ment.
       \n[sb]         Maximum displacement of text baseline below its original
                      position after rendering into dummy environment by \w.
       \n[seconds]    Count of seconds elapsed in the minute (0–60).
       \n[skw]        Skew  of  last  glyph rendered into dummy environment by
                      \w.
       \n[slimit]     The maximum depth of troff’s internal input  stack.   If
                      ≤0,  there  is  no  limit:  recursion can continue until
                      available memory is exhausted.  The default is 1,000.
       \n[ssc]        Subscript correction of last glyph rendered  into  dummy
                      environment by \w.
       \n[st]         Maximum displacement of text baseline above its original
                      position after rendering into dummy environment by \w.
       \n[systat]     Return value of system() function; see .sy.
       \n[urx]        Upper‐right  x coordinate (in PostScript units) of Post‐
                      Script image; see .psbb.
       \n[ury]        Upper‐right y coordinate (in PostScript units) of  Post‐
                      Script image; see .psbb.
       \n[year]       Gregorian year.
       \n[yr]         Gregorian year minus 1900.

Using fonts
       In  digital  typography, a font is a collection of characters in a spe‐
       cific typeface that a device can render as glyphs at  a  desired  size.
       (Terminals  and  some output devices have fonts that render at only one
       or two sizes.  As examples of the latter, take the groff  lj4  device’s
       Lineprinter,  and lbp’s Courier and Elite faces.)  A roff formatter can
       change typefaces at any point in the text.  The basic faces are  a  set
       of  styles  combining  upright and slanted shapes with normal and heavy
       stroke weights: “R”, “I”, “B”, and “BI”—these stand  for  roman,  bold,
       italic,  and  bold‐italic.  For linguistic text, GNU troff groups type‐
       faces into families containing each of these styles.   (Font  designers
       prepare  families  such  that the styles share esthetic properties.)  A
       text font is thus often a family combined with a style, but it need not
       be: consider the  ps  and  pdf  devices’  ZCMI  (Zapf  Chancery  Medium
       italic)—often,  no other style of Zapf Chancery Medium is provided.  On
       typesetting devices, at least one special font is available, comprising
       unstyled glyphs for mathematical operators and other purposes.

       Like AT&T troff, GNU troff does not itself load or manipulate a digital
       font file; instead it works with a font description file  that  charac‐
       terizes it, including its glyph repertoire and the metrics (dimensions)
       of  each  glyph.   This information permits the formatter to accurately
       place glyphs with respect to each other.  Before using a font  descrip‐
       tion,  the formatter associates it with a mounting position, a place in
       an ordered list of available typefaces.  So that a document need not be
       strongly coupled to a specific font family, in GNU troff an output  de‐
       vice  can associate a style in the abstract sense with a mounting posi‐
       tion.  Thus the default family can be combined  with  a  style  dynami‐
       cally, producing a resolved font name.

       Fonts  often  have  trademarked names, and even Free Software fonts can
       require renaming upon modification.  groff maintains a convention  that
       a  device’s  serif font family is given the name T (“Times”), its sans‐
       serif family H (“Helvetica”), and its monospaced family C  (“Courier”).
       Historical  inertia has driven groff’s font identifiers to short upper‐
       case abbreviations of font names, as with TR, TB, TI, TBI, and  a  spe‐
       cial font S.

       The  default  family  used  with  abstract styles can be changed at any
       time; initially, it is T.  Typically, abstract styles are  arranged  in
       the  first  four  mounting positions in the order shown above.  The de‐
       fault mounting position, and therefore style, is always 1 (R).  By  is‐
       suing  appropriate  formatter  instructions, you can override these de‐
       faults before your document writes its first glyph.

       Terminal output devices cannot change font families  and  lack  special
       fonts.   They  support  style  changes  by overstriking, or by altering
       ISO 6429/ECMA‐48 graphic renditions (character cell attributes).

Hyphenation
       When filling, groff hyphenates words as needed  at  user‐specified  and
       automatically  determined  hyphenation  points.   Explicitly hyphenated
       words such as “mother‐in‐law” are always eligible  for  breaking  after
       each  of  their hyphens.  The hyphenation character \% and non‐printing
       break point \: escape sequences may be used to control the  hyphenation
       and  breaking  of  individual words.  The .hw request sets user‐defined
       hyphenation points for specified words at  any  subsequent  occurrence.
       Otherwise,  groff  determines  hyphenation  points automatically by de‐
       fault.

       Several requests influence automatic hyphenation.  Because  conventions
       vary,  a  variety of hyphenation modes is available to the .hy request;
       these determine whether hyphenation will  apply  to  a  word  prior  to
       breaking  a  line at the end of a page (more or less; see below for de‐
       tails), and at which positions within that  word  automatically  deter‐
       mined  hyphenation points are permissible.  The default is “1” for his‐
       torical reasons, but this is not an appropriate value for  the  English
       hyphenation  patterns used by groff; localization macro files loaded by
       troffrc and macro packages often override it.

       0      disables hyphenation.

       1      enables hyphenation except after the first and before  the  last
              character of a word.

       The  remaining values “imply” 1; that is, they enable hyphenation under
       the same conditions as “.hy 1”, and then  apply  or  lift  restrictions
       relative to that basis.

       2      disables  hyphenation  of the last word on a page.  (Hyphenation
              is prevented if the next page location trap  is  closer  to  the
              vertical  drawing position than the next text baseline would be.
              See section “Traps” below.)

       4      disables hyphenation before the last two characters of a word.

       8      disables hyphenation after the first two characters of a word.

       16     enables hyphenation before the last character of a word.

       32     enables hyphenation after the first character of a word.

       Apart from value 2, restrictions imposed by the  hyphenation  mode  are
       not respected for words whose hyphenations have been specified with the
       hyphenation character (“\%” by default) or the .hw request.

       Nonzero  values are additive.  For example, mode 12 causes groff to hy‐
       phenate neither the last two nor the first two characters  of  a  word.
       Some  values  cannot  be used together because they contradict; for in‐
       stance, values 4 and 16, and values 8 and 32.  As noted, it  is  super‐
       fluous to add 1 to any non‐zero even mode.

       The  places  within a word that are eligible for hyphenation are deter‐
       mined by language‐specific data (.hla, .hpf, and .hpfa) and  lettercase
       relationships  (.hcode  and  .hpfcode).   Furthermore, hyphenation of a
       word might be suppressed due to a limit on consecutive hyphenated lines
       (.hlm), a minimum line length threshold (.hym), or because the line can
       instead be adjusted with additional inter‐word space (.hys).

Localization
       The set of hyphenation patterns is associated with the hyphenation lan‐
       guage set by the .hla request.  The .hpf request is usually invoked  by
       a  localization file loaded by the troffrc file.  groff provides local‐
       ization files for several languages; see groff_tmac(5).

Writing macros
       The .de request defines a macro named for its argument.  If  that  name
       already  exists  as an alias, the target of the alias is redefined; see
       section “Strings” above.  troff enters “copy mode” (see below), storing
       subsequent input lines as the definition.  If the optional second argu‐
       ment is not specified, the definition ends with the control  line  “..”
       (two  dots).  Alternatively, a second argument names a macro whose call
       syntax ends the definition; this “end macro” is then  called  normally.
       Spaces  or  tabs are permitted after the first control character in the
       line containing this ending token, but a tab immediately after the  to‐
       ken  prevents  its recognition as the end of a macro definition.  Macro
       definitions can be nested if they use distinct end macros or  if  their
       ending  tokens  are sufficiently escaped.  An end macro need not be de‐
       fined until it is called.  This fact enables a nested macro  definition
       to begin inside one macro and end inside another.

       Variants of .de disable compatibility mode and/or indirect the names of
       the  macros  specified  for  definition or termination: these are .de1,
       .dei, and .dei1.  Append to macro definitions with .am, .am1, .ami, and
       .ami1.  The .als, .rm, and .rn requests create an alias of, remove, and
       rename a macro, respectively.  .return stops the execution of  a  macro
       immediately, returning to the enclosing context.

   Parameters
       Macro  call  and  string interpolation parameters can be accessed using
       escape sequences starting with “\$”.   The  \n[.$]  read‐only  register
       stores  the  count  of  parameters  available to a macro or string; its
       value can be changed by the .shift request, which  dequeues  parameters
       from  the  current list.  The \$0 escape sequence interpolates the name
       by which a macro was called.  Applying string interpolation to a  macro
       does not change this name.

   Copy mode
       When troff processes certain requests, most importantly those which de‐
       fine or append to a macro or string, it does so in copy mode: it copies
       the  characters  of the definition into a dedicated storage region, in‐
       terpolating the escape sequences \n, \g, \$, \*, \V, and  \?  normally;
       interpreting  \newline  immediately; discarding comments \" and \#; in‐
       terpolating the current leader, escape, or tab character with  \a,  \e,
       and  \t, respectively; and storing all other escape sequences in an en‐
       coded form.  The complement of copy mode—a  roff  formatter’s  behavior
       when  not  defining or appending to a macro, string, or diversion—where
       all macros are interpolated, requests invoked,  and  valid  escape  se‐
       quences processed immediately upon recognition, can be termed interpre‐
       tation mode.

       The  escape  character,  \ by default, can escape itself.  This enables
       you to control whether a given \n, \g, \$, \*, \V,  or  \?  escape  se‐
       quence  is  interpreted at the time the macro containing it is defined,
       or later when the macro is called.

       You can think of \\ as a “delayed” backslash; it is the escape  charac‐
       ter followed by a backslash from which the escape character has removed
       its special meaning.  Consequently, \\ is not an escape sequence in the
       usual  sense.  In any escape sequence \X that troff does not recognize,
       the escape character is ignored and X is output.  An  unrecognized  es‐
       cape  sequence  causes  a warning in category “escape”, with two excep‐
       tions, \\ being one.  The other is \., which escapes the control  char‐
       acter.   It is used to permit nested macro definitions to end without a
       named macro call to conclude them.  Without a syntax for  escaping  the
       control  character,  this would not be possible.  roff documents should
       not use the \\ or \. character sequences outside  of  copy  mode;  they
       serve  only  to  obfuscate  the  input.  Use \e to represent the escape
       character, \[rs] to obtain a backslash glyph, and \&  before  .  and  '
       where  troff expects them as control characters if you mean to use them
       literally.

       Macro definitions can be nested to arbitrary depth.  In “\\”, each  es‐
       cape  character  is interpreted twice—once in copy mode, when the macro
       is defined, and once in interpretation mode, when the macro is  called.
       This fact leads to exponential growth in the quantity of escape charac‐
       ters  required  to delay interpolation of \n, \g, \$, \*, \V, and \? at
       each nesting level.  An alternative is to use \E, which  represents  an
       escape  character  that is not interpreted in copy mode.  Because \. is
       not a true escape sequence, we can’t use \E to keep “..” from ending  a
       macro  definition prematurely.  If the multiplicity of backslashes com‐
       plicates maintenance, use end macros.

Traps
       Traps are locations in the output, or conditions  on  the  input  that,
       when reached or fulfilled, call a specified macro.  A vertical position
       trap  calls  a  macro  when  the  formatter’s vertical drawing position
       reaches or passes, in the downward direction, a certain location on the
       output page or in a diversion.  Its applications include  setting  page
       headers  and  footers,  body  text  in multiple columns, and footnotes.
       These traps can occur at a given location on the page (.wh, .ch); at  a
       given location in the current diversion (.dt)—together, these are known
       as  vertical  position  traps,  which  can  be  disabled and re‐enabled
       (.vpt).

       A diversion is not formatted in the context of a page, so it lacks page
       location traps; instead it can have a diversion trap.  There can  exist
       at most one such vertical position trap per diversion.

       Other  kinds  of  trap can be planted at a blank line (.blm); at a line
       with leading space characters (.lsm); after a certain number of produc‐
       tive input lines (.it, .itc); or at the end  of  input  (.em).   Macros
       called by traps are passed no arguments.  Setting a trap is also called
       planting  one.   It  is  said that a trap is sprung if its condition is
       fulfilled.

       Registers associated with trap  management  include  vertical  position
       trap  enablement status (\n[.vpt]), distance to the next trap (\n[.t]),
       amount of needed (.ne‐requested) space that caused the most recent ver‐
       tical position trap to be sprung  (\n[.ne]),  amount  of  needed  space
       truncated  from the amount requested (\n[.trunc]), page ejection status
       (\n[.pe]), and leading space count (\n[.lsn])  with  its  corresponding
       amount of motion (\n[.lss]).

   Page location traps
       A  page  location  trap is a vertical position trap that applies to the
       page; that is, to undiverted output.  Many can be present; manage  them
       with  the  wh  and  ch  requests.  Non‐negative page locations given to
       these requests set the trap relative to the top of the  page;  negative
       values set the trap relative to the bottom of the page.  It is not pos‐
       sible  to plant a trap less than one basic unit from the page bottom: a
       location of “-0” is interpreted as “0”, the top of the page.  An exist‐
       ing visible trap (see below) at the same location is removed;  this  is
       .wh’s sole function if its second argument is missing.

       A  trap  is  sprung only if it is visible, meaning that its location is
       reachable on the page and it is not hidden by another trap at the  same
       location  already  planted  there.   (A trap planted at “20i” or “-30i”
       will not be sprung on a page of length “11i”.)

       A trap above the top or at or below the bottom of the page can be  made
       visible  by  either moving it into the page area or increasing the page
       length so that the trap is on the page.  Negative  trap  values  always
       use the current page length; they are not converted to an absolute ver‐
       tical  position.   Use .ptr to dump page location traps to the standard
       error stream; their positions are reported in basic units.

   The implicit page trap
       An implicit page trap always exists  in  the  top‐level  diversion;  it
       works like a trap in some ways but not others.  Its purpose is to eject
       the  current page and start the next one.  It has no name, so it cannot
       be moved or deleted with wh or ch requests.   You  cannot  hide  it  by
       placing  another trap at its location, and can move it only by redefin‐
       ing the page length with .pl.  Its operation is suppressed when  verti‐
       cal page traps are disabled with the vpt request.

Diversions
       In roff systems it is possible to format text as if for output, but in‐
       stead of writing it immediately, one can divert the formatted text into
       a named storage area.  It is retrieved later by specifying its name af‐
       ter  a  control character.  The same name space is used for such diver‐
       sions as for strings and macros; see section “Identifiers” above.  Such
       text is sometimes said to be “stored in a macro”, but this coinage  ob‐
       scures the important distinction between macros and strings on one hand
       and  diversions  on the other; the former store unformatted input text,
       and the latter capture formatted output.  Diversions also do not inter‐
       pret arguments.  Applications of diversions include “keeps” (preventing
       a page break from occurring at an inconvenient place by forcing  a  set
       of  output  lines to be set as a group), footnotes, tables of contents,
       and indices.  For orthogonality it is said that GNU  troff  is  in  the
       top‐level  diversion if no diversion is active (that is, formatted out‐
       put is being “diverted” immediately to the output device.

       Dereferencing an undefined diversion will create an empty one  of  that
       name  and  cause a warning in category mac to be emitted.  (see section
       “Warnings” in troff(1)).  A diversion does not exist for the purpose of
       testing with the d conditional operator until  its  initial  definition
       ends (see subsection “Conditional expressions” above).

       The  di  request creates a diversion, including any partially collected
       line.  da appends to a diversion, creating one if it does  not  already
       exist.   If the diversion’s name already exists as an alias, the target
       of the alias is replaced or appended to; see section  “Strings”  above.
       box  and  boxa  works  similarly, but ignore partially collected lines.
       Call any of these macros again without an argument to  end  the  diver‐
       sion.

       Diversions  can be nested.  The registers .d, .z, dn, and dl report in‐
       formation about the current (or last closed) diversion.  .h is meaning‐
       ful in diversions, including the top level.

       The \!  and \?  escape sequences and output request escape from  a  di‐
       version,  the  first two to the enclosing level and the last to the top
       level.  This facility is termed transparent embedding.

       The asciify and unformat requests reprocess diversions.

Punning names
       Macros, strings, and diversions share a name space; see section  “Iden‐
       tifiers”  above.  Internally, the same mechanism is used to store them.
       You can thus call a macro with string  interpolation  syntax  and  vice
       versa.   Interpolating a string does not hide existing macro arguments.
       The sequence \\ can be placed at the end of a line in a  macro  defini‐
       tion or, within a macro definition, immediately after the interpolation
       of a macro as a string to suppress the effect of a newline.

Environments
       Environments store most of the parameters that control text processing.
       A default environment named “0” exists when troff starts up; it is mod‐
       ified by formatting‐related requests and escape sequences.

       You  can  create  new  environments and switch among them.  Only one is
       current at any given time.  Active environments  are  managed  using  a
       stack,  a  data  structure supporting “push” and “pop” operations.  The
       current environment is at the top of the stack.  The  same  environment
       name  can be pushed onto the stack multiple times, possibly interleaved
       with others.  Popping the environment stack does not destroy  the  cur‐
       rent environment; it remains accessible by name and can be made current
       again  by  pushing  it  at any time.  Environments cannot be renamed or
       deleted, and can only be modified when current.  To inspect  the  envi‐
       ronment stack, use the pev request; see section “Debugging” below.

       Environments store the following information.

       • a partially collected line, if any

       • data  about  the most recently output glyph and line (registers .cdp,
         .cht, .csk, .n, .w)

       • typeface parameters (size, family, style, height  and  slant,  inter‐
         word and inter‐sentence space sizes)

       • page  parameters  (line  length, title length, vertical spacing, line
         spacing, indentation, line numbering, centering, right‐alignment, un‐
         derlining, hyphenation parameters)

       • filling enablement; adjustment enablement and mode

       • tab stops; tab, leader, escape, control,  no‐break  control,  hyphen‐
         ation, and margin characters

       • input line traps

       • stroke and fill colors

       The ev request pushes to and pops from the environment stack, while evc
       copies a named environment’s contents to the current one.

Underlining
       In  RUNOFF  (see  roff(7)),  underlining, even of lengthy passages, was
       straightforward because only fixed‐pitch  printing  devices  were  tar‐
       geted.   Typesetter  output  posed a greater challenge.  There exists a
       groff request .ul (see above) that underlines subsequent  source  lines
       on  terminal  devices,  but  on  typesetters, it selects an italic font
       style instead.  The ms macro package (see groff_ms(7)) offers  a  macro
       .UL,  but  it  too produces the desired effect only on typesetters, and
       has other limitations.

       One could adapt ms’s approach to the construction of a  macro  as  fol‐
       lows.
              .de UNDERLINE
              . ie n \\$1\f[I]\\$2\f[P]\\$3
              . el \\$1\Z'\\$2'\v'.25m'\D'l \w'\\$2'u 0'\v'-.25m'\\$3
              ..
       If  doclifter(1)  makes  trouble,  change the macro name UNDERLINE into
       some 2‐letter word, like Ul.  Moreover, change the form of the font se‐
       lection escape sequence from \f[P] to \fP.

   Underlining without macro definitions
       If one does not want to use macro  definitions,  e.g.,  when  doclifter
       gets lost, use the following.
              .ds u1 before
              .ds u2 in
              .ds u3 after
              .ie n \*[u1]\f[I]\*[u2]\f[P]\*[u3]
              .el \*[u1]\Z'\*[u2]'\v'.25m'\D'l \w'\*[u2]'u 0'\v'-.25m'\*[u3]
       When using doclifter, it might be necessary to change syntax forms such
       as  \[xy]  and \*[xy] to those supported by AT&T troff: \*(xy and \(xy,
       and so on.

       Then these lines could look like
              .ds u1 before
              .ds u2 in
              .ds u3 after
              .ie n \*[u1]\fI\*(u2\fP\*(u3
              .el \*(u1\Z'\*(u2'\v'.25m'\D'l \w'\*(u2'u 0'\v'-.25m'\*(u3

       The result looks like
              before _i_n after

   Underlining by overstriking with \(ul
       The \z escape sequence writes a glyph without advancing the drawing po‐
       sition, enabling overstriking.  Thus, \zc\(ul formats c with an  under‐
       rule  glyph  on  top of it.  Video terminals implement the underrule by
       setting a character cell’s underline attribute, so this technique works
       in both nroff and troff modes.

       Long words may then look intimidating in the input;  a  clarifying  ap‐
       proach  might  be  to  use  the input line continuation escape sequence
       \newline to place each underlined character  on  its  own  input  line.
       Thus,
              .nf
              \&\fB: ${\fIvar\fR\c
              \zo\(ul\
              \zp\(ul\c
              \&\fIvalue\fB}
              .fi
       produces
              : ${varo_p_value}
       as output.

Compatibility mode
       The  differences  between the roff language recognized by GNU troff and
       that of AT&T troff, as well as the device, font, and device‐independent
       intermediate output formats described by CSTR  #54  are  documented  in
       groff_diff(7).  groff provides an AT&T compatibility mode.  The .cp re‐
       quest  and  registers  .C  and  .cp set and test the enablement of this
       mode.

Debugging
       Preprocessors use the .lf request to preserve the  identities  of  line
       numbers and names of input files.  groff emits a variety of error diag‐
       nostics and supports several categories of warning; the output of these
       can  be  selectively  suppressed with .warn (and see the -E, -w, and -W
       options of troff(1)).  A trace  of  the  formatter’s  input  processing
       stack  can  be  emitted  when  errors  or  warnings  occur  by means of
       troff(1)’s -b option, or produced on demand  with  the  .backtrace  re‐
       quest.   .tm,  .tmc, and .tm1 can be used to emit customized diagnostic
       messages or for instrumentation while  troubleshooting.   .ex  and  .ab
       cause  early  termination  with successful and error exit codes respec‐
       tively, to halt further processing when continuing would be  fruitless.
       Examine  the  state  of the formatter with requests that write lists of
       defined  names—macros,  strings,  and  diversions—(.pm);   environments
       (.pev),  registers  (.pnr), and page location traps (.ptr) to the stan‐
       dard error stream.

Authors
       This document was written by by Trent A. Fisher, Werner Lemberg, and G.
       Branden Robinson ⟨g.branden.robinson@gmail.com⟩.  Section “Underlining”
       was primarily written by Bernd Warken ⟨groff-bernd.warken-72@web.de⟩.

See also
       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is the primary groff manual.  You can browse it interactively
       with “info groff”.

       “Troff User’s Manual” by Joseph F. Ossanna, 1976 (revised by  Brian  W.
       Kernighan,  1992),  AT&T  Bell Laboratories Computing Science Technical
       Report No. 54, widely called simply “CSTR #54”, documents the language,
       device and font description file formats, and device‐independent output
       format referred to collectively in groff documentation as “AT&T troff”.

       “A Typesetter‐independent TROFF” by Brian W. Kernighan, 1982, AT&T Bell
       Laboratories Computing Science Technical Report No. 97 (CSTR #97), pro‐
       vides additional insights into the device  and  font  description  file
       formats and device‐independent output format.

       groff(1)
              is  the  preferred interface to the groff system; it manages the
              pipeline that carries a source document  through  preprocessors,
              the  troff formatter, and an output driver to viewable or print‐
              able form.  It also exhaustively lists the  man  pages  provided
              with the GNU roff system.

       groff_char(7)
              discusses  character encoding issues, escape sequences that pro‐
              duce glyphs, and enumerates groff’s predefined special character
              escape sequences.

       groff_diff(7)
              covers differences between the GNU troff formatter,  its  device
              and font description file formats, its device‐independent output
              format, and those of AT&T troff, whose design it reimplements.

       groff_font(5)
              describes  the formats of the files that describe devices (DESC)
              and fonts.

       groff_tmac(5)
              surveys macro packages provided with groff, describes how  docu‐
              ments  can  take  advantage  of them, offers guidance on writing
              macro packages and using diversions, and includes historical in‐
              formation on macro package naming conventions.

       roff(7)
              presents a detailed history of roff systems and summarizes  con‐
              cepts common to them.

groff 1.23.0                      2 July 2023                         groff(7)
───────────────────────────────────────────────────────────────────────────────
groff_char(7)          Miscellaneous Information Manual          groff_char(7)

Name
       groff_char - GNU roff special character and glyph repertoire

Description
       The  GNU  roff typesetting system has a large glyph repertoire suitable
       for production of varied literary, professional, technical, and  mathe‐
       matical  documents.  groff works with characters; an output device ren‐
       ders glyphs.  groff’s input character set is restricted to that defined
       by the standards ISO Latin‐1 (ISO 8859‐1) and CCSID  “code  page”  1047
       (an  EBCDIC  arrangement of Latin‐1).  For ease of document maintenance
       in UTF‐8 environments, it is advisable to use only  the  Unicode  basic
       Latin  code  points,  a subset of all of the foregoing historically re‐
       ferred to as US‐ASCII,  which  has  only  94  visible,  printable  code
       points.   In  groff, these are termed ordinary characters.  Often, many
       more are desired in output.

       AT&T troff in the 1970s faced a similar problem: the available typeset‐
       ter’s glyph repertoire differed from that of the  computers  that  con‐
       trolled  it.  troff’s solution was a form of escape sequence known as a
       special character to access several dozen additional  glyphs  available
       in  the  fonts  prepared  for  mounting  in the phototypesetter.  These
       glyphs were mapped onto a two‐character name  space  for  a  degree  of
       mnemonic  convenience; for example, the escape sequence \(aa encoded an
       acute accent and \(sc a section sign.

       groff has lifted historical roff limitations on special character  name
       lengths,  but  recognizes and retains compatibility with the historical
       names.  groff expands the lexicon of glyphs available by name and  per‐
       mits  users to define their own special character escape sequences with
       the char request.  Special character names are groff  identifiers;  see
       section  “Identifiers”  in  groff(7).   Our  discussion  uses the terms
       “glyph name” and “special character name” interchangeably; we assume no
       character translations or redefinitions.

       This document lists all of the glyph names predefined by  groff’s  font
       description  files and presents the systematic notation by which it en‐
       ables access to arbitrary Unicode code points and construction of  com‐
       posite  glyphs.   Glyphs  listed may be unavailable, or may vary in ap‐
       pearance, depending on the output device and font chosen when the  page
       was formatted.  This page was rendered for device utf8 using font R.

       A  few escape sequences that are not groff special characters also pro‐
       duce glyphs; these exist for syntactical or  historical  reasons.   \',
       \`,  \-, and \_ are translated on input to the special character escape
       sequences \[aa], \[ga], \[-], and \[ul], respectively.  Others  include
       \\,  \.  (backslash‐dot), and \e; see groff(7).  A small number of spe‐
       cial characters represent glyphs that are not encoded in Unicode; exam‐
       ples include the baseline rule \[ru] and the Bell System logo \[bs].

       In groff, you can test output device support for any  character  (ordi‐
       nary or special) with the conditional expression operator “c”.
              .ie c \[bs] \{Welcome to the \[bs] Bell System;
              did you get the Wehrmacht helmet or the Death Star?\}
              .el No Bell System logo.

       For  brevity  in the remainder of this document, we shall refer to sys‐
       tems conforming to the ISO 646:1991 IRV, ISO 8859, or ISO 10646  (“Uni‐
       code”) character encoding standards as “ISO” systems, and those employ‐
       ing  IBM code page 1047 as “EBCDIC” systems.  That said, EBCDIC systems
       that support groff are known to also support UTF‐8.

       While groff accepts eight‐bit encoded input, not all such  code  points
       are  valid  as  input.  On ISO platforms, character codes 0, 11, 13–31,
       and 128–159 are invalid.  (This is all C0 and C1  controls  except  for
       SOH  through  LF  [Control+A  to  Control+J],  and FF [Control+L].)  On
       EBCDIC platforms, 0, 8–9, 11, 13–20,  23–31,  and  48–63  are  invalid.
       Some  of  these  code  points  are used by groff for internal purposes,
       which is one reason it does not support UTF‐8 natively.

   Fundamental character set
       The ordinary characters catalogued above, plus the space, tab, newline,
       and leader (Control+A), form the fundamental character  set  for  groff
       input;  anything  in the language, even over one million code points in
       Unicode, can be expressed using it.  On ISO systems, code points in the
       range 33–126 comprise a common set of printable glyphs in  all  of  the
       aforementioned  ISO character encoding standards.  It is this character
       set and (with  some  noteworthy  exceptions)  the  corresponding  glyph
       repertoire  for  which  AT&T troff was implemented.  On EBCDIC systems,
       printable characters are in the range 66–201 and 203–254; those without
       counterparts in the ISO range 33–126 are discussed in the next  subsec‐
       tion.

       All of the following characters map to glyphs as you would expect.
           ┌───────────────────────────────────────────────────────────┐
           │ ! # $ % & ( ) * + , . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @ │
           │ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ ] _ │
           │ a b c d e f g h i j k l m n o p q r s t u v w x y z { | } │
           └───────────────────────────────────────────────────────────┘
       The  remaining ordinary characters surprise computing professionals and
       others intimately familiar with the ISO character encodings.   The  de‐
       velopers of AT&T troff chose mappings for them that would be useful for
       typesetting  technical literature in a broad range of scientific disci‐
       plines: Bell Labs used the system for preparation of AT&T’s patent fil‐
       ings with the U.S. government.  Further, the prevailing  character  en‐
       coding  standard  in  the 1970s, USAS X3.4‐1968 (“ASCII”), deliberately
       supported semantic ambiguity at some code points, and outright  substi‐
       tution  at  several others, to suit the localization demands of various
       national standards bodies.

       The table below presents the seven exceptional code points  with  their
       typical  keycap  engravings, their glyph mappings and semantics in roff
       systems, and the escape sequences producing  the  Unicode  basic  Latin
       character they replace.  The first, the neutral double quote, is a par‐
       tial  exception  because  it  does represent itself, but since the roff
       language also uses it to quote macro arguments, groff supports  a  spe‐
       cial character escape sequence as an alternative form so that the glyph
       can be easily included in macro arguments without requiring the user to
       master  the  quoting  rules  that  AT&T troff required in that context.
       (Some requests, like ds, also treat " non‐literally.)  Furthermore, not
       all of the special character escape  sequences  are  portable  to  AT&T
       troff  and all of its descendants; these groff extensions are presented
       using its special character form \[], whereas portable special  charac‐
       ter  escape  sequences are shown in the traditional \( form.  \- and \e
       are portable to all known troffs.  \e means “the glyph of  the  current
       escape character”; it therefore can produce unexpected output if the ec
       request is used.  On devices with a limited glyph repertoire, glyphs in
       the  “keycap” and “appearance” columns on the same row of the table may
       look identical; except for the neutral double quote, this will  not  be
       the  case  on more‐capable devices.  Review your document using as many
       different output devices as possible.

       ┌───────────────────────────────────────────────────────────────────┐
       │ Keycap   Appearance and meaning   Special character and meaning   │
       ├───────────────────────────────────────────────────────────────────┤
       │ "        " neutral double quote   \[dq] neutral double quote      │
       │ '        ’ closing single quote   \[aq] neutral apostrophe        │
       │ -        ‐ hyphen                 \- or \[-] minus sign/Unix dash │
       │ \        (escape character)       \e or \[rs] reverse solidus     │
       │ ^        ˆ modifier circumflex    \(ha circumflex/caret/“hat”     │
       │ `        ‘ opening single quote   \(ga grave accent               │
       │ ~        ˜ modifier tilde         \(ti tilde                      │
       └───────────────────────────────────────────────────────────────────┘

       The hyphen‐minus is a particularly  unfortunate  case  of  overloading.
       Its awkward name in ISO 8859 and later standards reflects the many dis‐
       tinguishable  purposes  to  which it had already been put by the 1980s,
       including a hyphen, a minus sign, and (alone or in  repetition)  dashes
       of varying widths.  For best results in roff systems, use the “-” char‐
       acter  in input outside an escape sequence only to mean a hyphen, as in
       the phrase “long‐term”.  For a minus sign in running  text  or  a  Unix
       command‐line option dash, use \- (or \[-] in groff if you find it helps
       the  clarity  of the source document).  (Another minus sign, for use in
       mathematical equations, is available as \[mi]).  AT&T  troff  supported
       em‐dashes as \(em, as does groff.

       The  special  character escape sequence for the apostrophe as a neutral
       single quote is typically needed  only  in  technical  content;  typing
       words like “can’t” and “Anne’s” in a natural way will render correctly,
       because  in ordinary prose an apostrophe is typeset either as a closing
       single quotation mark or as a neutral single quote,  depending  on  the
       capabilities  of the output device.  By contrast, special character es‐
       cape sequences should be used for quotation marks unless portability to
       limited or historical troff implementations is necessary; on those sys‐
       tems, the input convention is to pair the grave accent with  the  apos‐
       trophe  for  single  quotes,  and  to double both characters for double
       quotes.  AT&T troff defined no special characters for  quotation  marks
       or  the apostrophe.  Repeated single quotes (‘‘thus’’) will be visually
       distinguishable from double quotes (“thus”) on  terminal  devices,  and
       perhaps on others (depending on the font selected).
        ┌─────────────────────────────────────────────────────────────────┐
        │ AT&T troff input          recommended groff input               │
        ├─────────────────────────────────────────────────────────────────┤
        │ A Winter's Tale           A Winter's Tale                       │
        │ `U.K. outer quotes'       \[oq]U.K. outer quotes\[cq]           │
        │ `U.K. ``inner'' quotes'   \[oq]U.K. \[lq]inner\[rq] quotes\[cq] │
        │ ``U.S. outer quotes''     \[lq]U.S. outer quotes\[rq]           │
        │ ``U.S. `inner' quotes''   \[lq]U.S. \[oq]inner\[cq] quotes\[rq] │
        └─────────────────────────────────────────────────────────────────┘
       If  you frequently require quotation marks in your document, see if the
       macro package you’re using supplies strings  or  macros  to  facilitate
       quotation, or define them yourself (except in man pages).

       Using Unicode basic Latin characters to compose boxes and lines is ill‐
       advised.   roff  systems have special characters for drawing horizontal
       and vertical lines; see subsection “Rules and lines” below.  Preproces‐
       sors like tbl(1) and pic(1) draw boxes and will produce the best possi‐
       ble output for the device, falling back to basic Latin glyphs only when
       necessary.

   Eight‐bit encodings and Latin‐1 supplement
       ISO 646 is a seven‐bit code encoding 128 code points;  eight‐bit  codes
       are  twice the size.  ISO 8859‐1 and code page 1047 allocated the addi‐
       tional space to what Unicode calls “C1 controls”  (control  characters)
       and  the  “Latin‐1  supplement”.  The C1 controls are neither printable
       nor usable as groff input.

       Two Latin‐1 supplement  characters  are  handled  specially  on  input.
       troff never produces them as output.

       NBSP   encodes  a  no‐break  space;  it is mapped to \~, the adjustable
              non‐breaking space escape sequence.

       SHY    encodes a soft hyphen; it is mapped to \%, the hyphenation  con‐
              trol escape sequence.

       The  remaining  characters  in  the  Latin‐1 supplement represent them‐
       selves.  Although they can be specified directly with the  keyboard  on
       systems configured to use Latin‐1 as the character encoding, it is more
       portable,  both to other roff systems and to UTF‐8 environments, to use
       their special character escape sequences, shown below.  The  glyph  de‐
       scriptions we use are non‐standard in some cases, for brevity.

       ¡  \[r!] inverted exclamation mark     Ñ  \[~N] N tilde
       ¢  \[ct] cent sign                     Ò  \[`O] O grave
       £  \[Po] pound sign                    Ó  \['O] O acute
       ¤  \[Cs] currency sign                 Ô  \[^O] O circumflex
       ¥  \[Ye] yen sign                      Õ  \[~O] O tilde
       ¦  \[bb] broken bar                    Ö  \[:O] O dieresis
       §  \[sc] section sign                  ×  \[mu] multiplication sign
       ¨  \[ad] dieresis accent               Ø  \[/O] O slash
       ©  \[co] copyright sign                Ù  \[`U] U grave
       ª  \[Of] feminine ordinal indicator    Ú  \['U] U acute
       «  \[Fo] left double chevron           Û  \[^U] U circumflex
       ¬  \[no] logical not                   Ü  \[:U] U dieresis
       ®  \[rg] registered sign               Ý  \['Y] Y acute
       ¯  \[a-] macron accent                 Þ  \[TP] uppercase thorn
       °  \[de] degree sign                   ß  \[ss] lowercase sharp s
       ±  \[+-] plus‐minus                    à  \[`a] a grave
       ²  \[S2] superscript two               á  \['a] a acute
       ³  \[S3] superscript three             â  \[^a] a circumflex
       ´  \[aa] acute accent                  ã  \[~a] a tilde
       µ  \[mc] micro sign                    ä  \[:a] a dieresis
       ¶  \[ps] pilcrow sign                  å  \[oa] a ring
       ·  \[pc] centered period               æ  \[ae] ae ligature
       ¸  \[ac] cedilla accent                ç  \[,c] c cedilla
       ¹  \[S1] superscript one               è  \[`e] e grave
       º  \[Om] masculine ordinal indicator   é  \['e] e acute
       »  \[Fc] right double chevron          ê  \[^e] e circumflex
       ¼  \[14] one quarter symbol            ë  \[:e] e dieresis
       ½  \[12] one half symbol               ì  \[`i] i grave
       ¾  \[34] three quarters symbol         í  \['i] e acute
       ¿  \[r?] inverted question mark        î  \[^i] i circumflex
       À  \[`A] A grave                       ï  \[:i] i dieresis
       Á  \['A] A acute                       ð  \[Sd] lowercase eth
       Â  \[^A] A circumflex                  ñ  \[~n] n tilde
       Ã  \[~A] A tilde                       ò  \[`o] o grave
       Ä  \[:A] A dieresis                    ó  \['o] o acute
       Å  \[oA] A ring                        ô  \[^o] o circumflex
       Æ  \[AE] AE ligature                   õ  \[~o] o tilde
       Ç  \[,C] C cedilla                     ö  \[:o] o dieresis
       È  \[`E] E grave                       ÷  \[di] division sign
       É  \['E] E acute                       ø  \[/o] o slash
       Ê  \[^E] E circumflex                  ù  \[`u] u grave
       Ë  \[:E] E dieresis                    ú  \['u] u acute
       Ì  \[`I] I grave                       û  \[^u] u circumflex
       Í  \['I] I acute                       ü  \[:u] u dieresis
       Î  \[^I] I circumflex                  ý  \['y] y acute
       Ï  \[:I] I dieresis                    þ  \[Tp] lowercase thorn
       Ð  \[-D] uppercase eth                 ÿ  \[:y] y dieresis

   Special character escape forms
       Glyphs  that lack a character code in the basic Latin repertoire to di‐
       rectly represent them are entered by one of several  special  character
       escape forms.  Such glyphs can be simple or composite, and accessed ei‐
       ther  by  name or numerically by code point.  Code points and combining
       properties are determined  by  character  encoding  standards,  whereas
       glyph names as used here originated in AT&T troff special character es‐
       cape  sequences.  Predefined glyph names use only characters in the ba‐
       sic Latin repertoire.

       \(gl   is a special character escape sequence for the  glyph  with  the
              two‐character  name  gl.   This is the original syntax form sup‐
              ported by AT&T troff.  The acute accent, \(aa, is an example.

       \C'glyph‐name'
              is a special character escape sequence for glyph‐name, which can
              be of arbitrary length.  The delimiter, shown here as a  neutral
              apostrophe,  can  be  any character not occurring in glyph‐name.
              This syntax form was introduced in later versions  of  AT&T  de‐
              vice‐independent  troff.  The foregoing acute accent example can
              be expressed as \C'aa'.

       \[glyph‐name]
              is a special character escape sequence for glyph‐name, which can
              be of arbitrary length but must not  contain  a  closing  square
              bracket  “]”.   (No glyph names predefined by groff employ “]”.)
              The foregoing acute accent example can be expressed in groff  as
              \[aa].

       \C'c' and \[c] are not synonyms for the ordinary character “c”, but re‐
       quest  the  special  character  named “\c”.  For example, “\[a]” is not
       “a”, but rather a special character with the internal glyph name  (used
       in  font  description files and diagnostic messages) \a, which is typi‐
       cally undefined.  The only such glyph name groff predefines is the  mi‐
       nus sign, which can therefore be accessed as \C'-' or \[-].

       \[base‐char composite‐1 composite‐2 ... composite‐n]
              is a composite glyph.  Glyphs like a lowercase “e” with an acute
              accent, as in the word “café”, can be expressed as \[e aa].  See
              subsection “Accents” below for a table of combining glyph names.

       Unicode  encodes  far  more  characters than groff has glyph names for;
       special character escape forms based on numerical  code  points  enable
       access  to  any  of them.  Frequently used glyphs or glyph combinations
       can be stored in strings, and new glyph names can  be  created  ad  hoc
       with the char request; see groff(7).

       \[unnnn[n[n]]]
              is  a  Unicode  numeric  special character escape sequence.  Any
              Unicode code point can be accessed with four to six  hexadecimal
              digits,  with  hexadecimal  letters  accepted  in uppercase form
              only.  Thus, \[u02DA] accesses the (spacing) ring  accent,  pro‐
              ducing “˚”.

       Unicode  code  points can be composed as well; when they are, GNU troff
       requires NFD (Normalization Form D), where all Unicode glyphs are maxi‐
       mally decomposed.  (Exception: precomposed characters  in  the  Latin‐1
       supplement described above are also accepted.  Do not count on this ex‐
       ception  remaining  in  a future GNU troff that accepts UTF‐8 input di‐
       rectly.)   Thus,  GNU  troff  accepts  “caf\['e]”,  “caf\[e  aa]”,  and
       “caf\[u0065_0301]”,  as ways to input “café”.  (Due to its legacy 8‐bit
       encoding compatibility, at present it also accepts “caf\[u00E9]” on ISO
       Latin‐1 systems.)

       \[ubase‐char[_combining‐component]...]
              constructs a composite glyph from Unicode numeric special  char‐
              acter  escape  sequences.  The code points of the base glyph and
              the combining components are each expressed in hexadecimal, with
              an   underscore   (_)   separating   each   component.     Thus,
              \[u006E_0303] produces “ñ”.

       \[charnnn]
              expresses an eight‐bit code point where nnn is the code point of
              the  character, a decimal number between 0 and 255 without lead‐
              ing zeroes.  This legacy numeric special  character  escape  se‐
              quence  is  used  to map characters onto glyphs via the trin re‐
              quest in macro files loaded by grotty(1).

Glyph tables
       In this section, groff’s glyph name repertoire is presented in  tabular
       form.  The meanings of the columns are as follows.

       Output  shows the glyph as it appears on the device used to render this
               document;  although  it  can  have a notably different shape on
               other devices (and is subject to user‐directed translation  and
               replacement), groff attempts reasonable equivalency on all out‐
               put devices.

       Input   shows  the  groff character (ordinary or special) that normally
               produces the glyph.   Some  code  points  have  multiple  glyph
               names.

       Unicode is the code point notation for the glyph or combining glyph se‐
               quence  as  described  in  subsection “Special character escape
               forms” above.  It corresponds to the standard notation for Uni‐
               code short identifiers such that groff’s unnnn is equivalent to
               Unicode’s U+nnnn.

       Notes   describes the glyph, elucidating  the  mnemonic  value  of  the
               glyph name where possible.

               A  plus  sign  “+” indicates that the glyph name appears in the
               AT&T troff user’s manual, CSTR #54 (1992 revision).  When using
               the AT&T special character syntax \(xx, widespread  portability
               can be expected from such names.

               Entries  marked  with “***” denote glyphs used for mathematical
               purposes.  On typesetting devices, such  glyphs  are  typically
               drawn  from  a  special  font (see groff_font(5)).  Often, such
               glyphs lack bold or italic style forms  or  have  metrics  that
               look incongruous in ordinary prose.  A few which are not uncom‐
               mon  in  running  text  have “text variants”, which should work
               better in that context.  Conversely, a handful of  glyphs  that
               are  normally  drawn from a text font may be required in mathe‐
               matical equations.  Both sets of exceptions are  noted  in  the
               tables  where  they appear (“Logical symbols” and “Mathematical
               symbols”).

   Basic Latin
       Apart from basic Latin characters with special mappings,  described  in
       subsection  “Fundamental  character  set”  above,  a few others in that
       range have special character glyph names.  These were defined for  ease
       of  input on non‐U.S. keyboards lacking keycaps for them, or for symme‐
       try with other special character glyph names serving a similar purpose.

       The vertical bar is overloaded; the \[ba] and  \[or]  escape  sequences
       may  render  differently.   See subsection “Mathematical symbols” below
       for special variants of the plus,  minus,  and  equals  signs  normally
       drawn from this range.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       "        \[dq]   u0022     neutral double quote
       #        \[sh]   u0023     number sign
       $        \[Do]   u0024     dollar sign
       '        \[aq]   u0027     apostrophe, neutral single quote
       /        \[sl]   u002F     slash, solidus +
       @        \[at]   u0040     at sign
       [        \[lB]   u005B     left square bracket
       \        \[rs]   u005C     reverse solidus
       ]        \[rB]   u005D     right square bracket
       ^        \[ha]   u005E     circumflex, caret, “hat”
       {        \[lC]   u007B     left brace
       |        |       u007C     bar
       |        \[ba]   u007C     bar
       |        \[or]   u007C     bitwise or +
       }        \[rC]   u007D     right brace
       ~        \[ti]   u007E     tilde

   Supplementary Latin letters
       Historically,  \[ss] could be considered a ligature of “sz”.  An upper‐
       case form is available as \[u1E9E], but in the German language it is of
       specialized use; ß does not normally  uppercase‐transform  to  it,  but
       rather  to  “SS”.   “Lowercase  f with hook” is also used as a function
       symbol; see subsection “Mathematical symbols” below.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       Ð        \[-D]   u00D0     uppercase eth
       ð        \[Sd]   u00F0     lowercase eth
       Þ        \[TP]   u00DE     uppercase thorn
       þ        \[Tp]   u00FE     lowercase thorn
       ß        \[ss]   u00DF     lowercase sharp s
       ı        \[.i]   u0131     i without tittle
       ȷ        \[.j]   u0237     j without tittle
       ƒ        \[Fn]   u0192     lowercase f with hook, function
       Ł        \[/L]   u0141     L with stroke
       ł        \[/l]   u0142     l with stroke
       Ø        \[/O]   u00D8     O with stroke
       ø        \[/o]   u00F8     o with stroke

   Ligatures and digraphs
       Output   Input   Unicode           Notes
       ────────────────────────────────────────────────────────────────────────
       ff       \[ff]   u0066_0066        ff ligature +
       fi       \[fi]   u0066_0069        fi ligature +
       fl       \[fl]   u0066_006C        fl ligature +
       ffi      \[Fi]   u0066_0066_0069   ffi ligature +
       ffl      \[Fl]   u0066_0066_006C   ffl ligature +
       Æ        \[AE]   u00C6             AE ligature
       æ        \[ae]   u00E6             ae ligature
       Π       \[OE]   u0152             OE ligature
       œ        \[oe]   u0153             oe ligature
       IJ        \[IJ]   u0132             IJ digraph
       ij        \[ij]   u0133             ij digraph

   Accents
       Normally, the formatting of a special character  advances  the  drawing
       position as an ordinary character does.  groff’s composite request des‐
       ignates  a  special  character  as combining.  The composite.tmac macro
       file, loaded automatically by the default troffrc, maps  the  following
       special  characters  to the combining characters shown below.  The non‐
       combining code point in parentheses is used when the special  character
       occurs in isolation (compare “caf\[e aa]” and “caf\[aa]e”).

       Output   Input   Unicode         Notes
       ────────────────────────────────────────────────────────────────────────
       ˝        \[a"]   u030B (u02DD)   double acute accent
       ¯        \[a-]   u0304 (u00AF)   macron accent
       ˙        \[a.]   u0307 (u02D9)   dot accent
       ^        \[a^]   u0302 (u005E)   circumflex accent
       ´        \[aa]   u0301 (u00B4)   acute accent +
       `        \[ga]   u0300 (u0060)   grave accent +
       ˘        \[ab]   u0306 (u02D8)   breve accent
       ¸        \[ac]   u0327 (u00B8)   cedilla accent
       ¨        \[ad]   u0308 (u00A8)   dieresis accent
       ˇ        \[ah]   u030C (u02C7)   caron accent
       ˚        \[ao]   u030A (u02DA)   ring accent
       ~        \[a~]   u0303 (u007E)   tilde accent
       ˛        \[ho]   u0328 (u02DB)   hook accent

   Accented characters
       All  of these glyphs can be composed using combining glyph names as de‐
       scribed in subsection “Special character escape forms” above; the names
       below are short aliases for convenience.

       Output   Input   Unicode      Notes
       ────────────────────────────────────────────────────────────────────────
       Á        \['A]   u0041_0301   A acute
       Ć        \['C]   u0043_0301   C acute
       É        \['E]   u0045_0301   E acute
       Í        \['I]   u0049_0301   I acute
       Ó        \['O]   u004F_0301   O acute
       Ú        \['U]   u0055_0301   U acute
       Ý        \['Y]   u0059_0301   Y acute
       á        \['a]   u0061_0301   a acute
       ć        \['c]   u0063_0301   c acute
       é        \['e]   u0065_0301   e acute
       í        \['i]   u0069_0301   i acute
       ó        \['o]   u006F_0301   o acute
       ú        \['u]   u0075_0301   u acute
       ý        \['y]   u0079_0301   y acute

       Ä        \[:A]   u0041_0308   A dieresis
       Ë        \[:E]   u0045_0308   E dieresis
       Ï        \[:I]   u0049_0308   I dieresis
       Ö        \[:O]   u004F_0308   O dieresis
       Ü        \[:U]   u0055_0308   U dieresis
       Ÿ        \[:Y]   u0059_0308   Y dieresis
       ä        \[:a]   u0061_0308   a dieresis
       ë        \[:e]   u0065_0308   e dieresis
       ï        \[:i]   u0069_0308   i dieresis
       ö        \[:o]   u006F_0308   o dieresis
       ü        \[:u]   u0075_0308   u dieresis
       ÿ        \[:y]   u0079_0308   y dieresis

       Â        \[^A]   u0041_0302   A circumflex
       Ê        \[^E]   u0045_0302   E circumflex
       Î        \[^I]   u0049_0302   I circumflex
       Ô        \[^O]   u004F_0302   O circumflex
       Û        \[^U]   u0055_0302   U circumflex
       â        \[^a]   u0061_0302   a circumflex
       ê        \[^e]   u0065_0302   e circumflex
       î        \[^i]   u0069_0302   i circumflex
       ô        \[^o]   u006F_0302   o circumflex
       û        \[^u]   u0075_0302   u circumflex

       À        \[`A]   u0041_0300   A grave
       È        \[`E]   u0045_0300   E grave
       Ì        \[`I]   u0049_0300   I grave
       Ò        \[`O]   u004F_0300   O grave
       Ù        \[`U]   u0055_0300   U grave
       à        \[`a]   u0061_0300   a grave
       è        \[`e]   u0065_0300   e grave
       ì        \[`i]   u0069_0300   i grave
       ò        \[`o]   u006F_0300   o grave
       ù        \[`u]   u0075_0300   u grave

       Ã        \[~A]   u0041_0303   A tilde
       Ñ        \[~N]   u004E_0303   N tilde
       Õ        \[~O]   u004F_0303   O tilde
       ã        \[~a]   u0061_0303   a tilde
       ñ        \[~n]   u006E_0303   n tilde
       õ        \[~o]   u006F_0303   o tilde

       Š        \[vS]   u0053_030C   S caron
       š        \[vs]   u0073_030C   s caron
       Ž        \[vZ]   u005A_030C   Z caron
       ž        \[vz]   u007A_030C   z caron

       Ç        \[,C]   u0043_0327   C cedilla
       ç        \[,c]   u0063_0327   c cedilla

       Å        \[oA]   u0041_030A   A ring
       å        \[oa]   u0061_030A   a ring

   Quotation marks
       The neutral double quote, often  useful  when  documenting  programming
       languages,  is also available as a special character for convenient em‐
       bedding in macro arguments; see subsection “Fundamental character  set”
       above.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       „        \[Bq]   u201E     low double comma quote
       ‚        \[bq]   u201A     low single comma quote
       “        \[lq]   u201C     left double quote
       ”        \[rq]   u201D     right double quote
       ‘        \[oq]   u2018     single opening (left) quote
       ’        \[cq]   u2019     single closing (right) quote
       '        \[aq]   u0027     apostrophe, neutral single quote
       "        "       u0022     neutral double quote
       "        \[dq]   u0022     neutral double quote
       «        \[Fo]   u00AB     left double chevron
       »        \[Fc]   u00BB     right double chevron
       ‹        \[fo]   u2039     left single chevron
       ›        \[fc]   u203A     right single chevron

   Punctuation
       The  Unicode  name  for  U+00B7 is “middle dot”, which is unfortunately
       confusable with the groff mnemonic for the visually similar but  seman‐
       tically  distinct multiplication dot; see subsection “Mathematical sym‐
       bols” below.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ¡        \[r!]   u00A1     inverted exclamation mark
       ¿        \[r?]   u00BF     inverted question mark
       ·        \[pc]   u00B7     centered period
       —        \[em]   u2014     em‐dash +
       –        \[en]   u2013     en‐dash
       ‐        \[hy]   u2010     hyphen +

   Brackets
       On typesetting  devices,  the  bracket  extensions  are  font‐invariant
       glyphs;  that  is,  they  are  rendered the same way regardless of font
       (with a drawing escape sequence).  On terminals, they are not  font‐in‐
       variant;  groff  maps them rather arbitrarily to U+23AA (“curly bracket
       extension”).  In AT&T troff, only one glyph was available to vertically
       extend brackets, braces, and parentheses: \(bv.

       Not all devices supply bracket pieces that can be piled up with \b  due
       to  the restrictions of the escape’s piling algorithm.  A general solu‐
       tion to build brackets out of pieces is the following macro:
              .\" Make a pile centered vertically 0.5em above the baseline.
              .\" The first argument is placed at the top.
              .\" The pile is returned in string 'pile'.
              .eo
              .de pile-make
              .  nr pile-wd 0
              .  nr pile-ht 0
              .  ds pile-args
              .
              .  nr pile-# \n[.$]
              .  while \n[pile-#] \{\
              .    nr pile-wd (\n[pile-wd] >? \w'\$[\n[pile-#]]')
              .    nr pile-ht +(\n[rst] - \n[rsb])
              .    as pile-args \v'\n[rsb]u'\"
              .    as pile-args \Z'\$[\n[pile-#]]'\"
              .    as pile-args \v'-\n[rst]u'\"
              .    nr pile-# -1
              .  \}
              .
              .  ds pile \v'(-0.5m + (\n[pile-ht]u / 2u))'\"
              .  as pile \*[pile-args]\"
              .  as pile \v'((\n[pile-ht]u / 2u) + 0.5m)'\"
              .  as pile \h'\n[pile-wd]u'\"
              ..
              .ec

       Another complication is the  fact  that  some  glyphs  which  represent
       bracket pieces in AT&T troff can be used for other mathematical symbols
       as  well,  for example \(lf and \(rf, which provide the floor operator.
       Some output devices, such as dvi, don’t unify such  glyphs.   For  this
       reason,  the glyphs \[lf], \[rf], \[lc], and \[rc] are not unified with
       similar‐looking bracket pieces.  In groff, only glyphs with long  names
       are  guaranteed  to  pile  up  correctly for all devices—provided those
       glyphs are available.

       Output   Input               Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       [        [                   u005B     left square bracket
       [        \[lB]               u005B     left square bracket
       ]        ]                   u005D     right square bracket
       ]        \[rB]               u005D     right square bracket
       {        {                   u007B     left brace
       {        \[lC]               u007B     left brace
       }        }                   u007D     right brace
       }        \[rC]               u007D     right brace
       ⟨        \[la]               u27E8     left angle bracket
       ⟩        \[ra]               u27E9     right angle bracket
       ⎪        \[bv]               u23AA     brace vertical extension + ***
       ⎪        \[braceex]          u23AA     brace vertical extension

       ⎡        \[bracketlefttp]    u23A1     left square bracket top
       ⎢        \[bracketleftex]    u23A2     left square bracket extension
       ⎣        \[bracketleftbt]    u23A3     left square bracket bottom

       ⎤        \[bracketrighttp]   u23A4     right square bracket top
       ⎥        \[bracketrightex]   u23A5     right square bracket extension
       ⎦        \[bracketrightbt]   u23A6     right square bracket bottom

       ⎧        \[lt]               u23A7     left brace top +
       ⎨        \[lk]               u23A8     left brace middle +
       ⎩        \[lb]               u23A9     left brace bottom +
       ⎧        \[bracelefttp]      u23A7     left brace top
       ⎨        \[braceleftmid]     u23A8     left brace middle
       ⎩        \[braceleftbt]      u23A9     left brace bottom
       ⎪        \[braceleftex]      u23AA     left brace extension

       ⎫        \[rt]               u23AB     right brace top +
       ⎬        \[rk]               u23AC     right brace middle +
       ⎭        \[rb]               u23AD     right brace bottom +
       ⎫        \[bracerighttp]     u23AB     right brace top
       ⎬        \[bracerightmid]    u23AC     right brace middle
       ⎭        \[bracerightbt]     u23AD     right brace bottom
       ⎪        \[bracerightex]     u23AA     right brace extension

       ⎛        \[parenlefttp]      u239B     left parenthesis top
       ⎜        \[parenleftex]      u239C     left parenthesis extension
       ⎝        \[parenleftbt]      u239D     left parenthesis bottom
       ⎞        \[parenrighttp]     u239E     right parenthesis top
       ⎟        \[parenrightex]     u239F     right parenthesis extension
       ⎠        \[parenrightbt]     u23A0     right parenthesis bottom

   Arrows
       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ←        \[<-]   u2190     horizontal arrow left +
       →        \[->]   u2192     horizontal arrow right +
       ↔        \[<>]   u2194     bidirectional horizontal arrow
       ↓        \[da]   u2193     vertical arrow down +
       ↑        \[ua]   u2191     vertical arrow up +
       ↕        \[va]   u2195     bidirectional vertical arrow
       ⇐        \[lA]   u21D0     horizontal double arrow left
       ⇒        \[rA]   u21D2     horizontal double arrow right
       ⇔        \[hA]   u21D4     bidirectional horizontal double arrow
       ⇓        \[dA]   u21D3     vertical double arrow down
       ⇑        \[uA]   u21D1     vertical double arrow up
       ⇕        \[vA]   u21D5     bidirectional vertical double arrow
       ⎯        \[an]   u23AF     horizontal arrow extension

   Rules and lines
       On typesetting  devices,  the  font‐invariant  glyphs  (see  subsection
       “Brackets”  above)  \[br], \[ul], and \[rn] form corners when adjacent;
       they can be used to build boxes.  On terminal devices, they are  mapped
       as shown in the table.  The Unicode‐derived names of these three glyphs
       are approximations.

       The  input  character _ always accesses the underscore glyph in a font;
       \[ul], by contrast, may be font‐invariant on typesetting devices.

       The baseline rule \[ru] is a font‐invariant glyph,  namely  a  rule  of
       one‐half em.

       In  AT&T  troff,  \[rn] also served as a one en extension of the square
       root symbol.  groff favors \[radicalex] for this purpose;  see  subsec‐
       tion “Mathematical symbols” below.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       |        |       u007C     bar
       |        \[ba]   u007C     bar
       │        \[br]   u2502     box rule +
       _        _       u005F     underscore, low line +
       _        \[ul]   ‐‐‐       underrule +
       ‾        \[rn]   u203E     overline +
       _        \[ru]   ‐‐‐       baseline rule +
       ¦        \[bb]   u00A6     broken bar
       /        /       u002F     slash, solidus +
       /        \[sl]   u002F     slash, solidus +
       \        \[rs]   u005C     reverse solidus

   Text markers
       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ○        \[ci]   u25CB     circle +
       •        \[bu]   u2022     bullet +
       †        \[dg]   u2020     dagger +
       ‡        \[dd]   u2021     double dagger +
       ◊        \[lz]   u25CA     lozenge, diamond
       □        \[sq]   u25A1     square +
       ¶        \[ps]   u00B6     pilcrow sign
       §        \[sc]   u00A7     section sign +
       ☜        \[lh]   u261C     hand pointing left +
       ☞        \[rh]   u261E     hand pointing right +
       @        @       u0040     at sign
       @        \[at]   u0040     at sign
       #        #       u0023     number sign
       #        \[sh]   u0023     number sign
       ↵        \[CR]   u21B5     carriage return
       ✓        \[OK]   u2713     check mark

   Legal symbols
       The Bell System logo is not supported in groff.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ©        \[co]   u00A9     copyright sign +
       ®        \[rg]   u00AE     registered sign +
       ™        \[tm]   u2122     trade mark sign
                \[bs]   ‐‐‐       Bell System logo +

   Currency symbols
       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       $        $       u0024     dollar sign
       $        \[Do]   u0024     dollar sign
       ¢        \[ct]   u00A2     cent sign +
       €        \[eu]   u20AC     Euro sign
       €        \[Eu]   u20AC     variant Euro sign
       ¥        \[Ye]   u00A5     yen sign
       £        \[Po]   u00A3     pound sign
       ¤        \[Cs]   u00A4     currency sign

   Units
       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       °        \[de]   u00B0     degree sign +
       ‰        \[%0]   u2030     per thousand, per mille sign
       ′        \[fm]   u2032     arc minute sign, foot mark +
       ″        \[sd]   u2033     arc second sign
       µ        \[mc]   u00B5     micro sign
       ª        \[Of]   u00AA     feminine ordinal indicator
       º        \[Om]   u00BA     masculine ordinal indicator

   Logical symbols
       The  variants  of  the not sign may differ in appearance or spacing de‐
       pending on the device and font selected.  Unicode  does  not  encode  a
       discrete “bitwise or” sign: on typesetting devices, it is drawn shorter
       than  the bar, about the same height as a capital letter.  Terminal de‐
       vices unify \[ba] and \[or].

       Output   Input    Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ∧        \[AN]    u2227     logical and
       ∨        \[OR]    u2228     logical or
       ¬        \[no]    u00AC     logical not + ***
       ¬        \[tno]   u00AC     text variant of \[no]
       ∃        \[te]    u2203     there exists
       ∀        \[fa]    u2200     for all
       ∋        \[st]    u220B     such that
       ∴        \[3d]    u2234     therefore
       ∴        \[tf]    u2234     therefore
       |        |        u007C     bar
       |        \[or]    u007C     bitwise or +

   Mathematical symbols
       \[Fn] also appears in subsection “Supplementary Latin  letters”  above.
       Observe  the two varieties of the plus‐minus, multiplication, and divi‐
       sion signs; \[+-], \[mu], and \[di] are normally drawn from the special
       font, but have text font variants.   Also  be  aware  of  three  glyphs
       available  in  special  font variants that are normally drawn from text
       fonts: the plus, minus, and equals signs.  These variants may differ in
       appearance or spacing depending on the device and font selected.

       In AT&T troff, \(rn (“root en extender”) served as the  horizontal  ex‐
       tension  of  the radical (square root) sign, \(sr, and was drawn at the
       maximum height of the typeface’s bounding box; this enabled the special
       character to double as an overline (see subsection  “Rules  and  lines”
       above).  A contemporary font’s radical sign might not ascend to such an
       extreme.   In  groff,  you can instead use \[radicalex] to continue the
       radical sign \[sr]; these special characters are intended for use  with
       text  fonts.   \[sqrt] and \[sqrtex] are their counterparts with mathe‐
       matical spacing.

       Output   Input          Unicode      Notes
       ────────────────────────────────────────────────────────────────────────
       ½        \[12]          u00BD        one half symbol +
       ¼        \[14]          u00BC        one quarter symbol +
       ¾        \[34]          u00BE        three quarters symbol +
       ⅛        \[18]          u215B        one eighth symbol
       ⅜        \[38]          u215C        three eighths symbol
       ⅝        \[58]          u215D        five eighths symbol
       ⅞        \[78]          u215E        seven eighths symbol
       ¹        \[S1]          u00B9        superscript one
       ²        \[S2]          u00B2        superscript two
       ³        \[S3]          u00B3        superscript three

       +        +              u002B        plus
       +        \[pl]          u002B        special variant of plus + ***
       -        \[-]           u002D        minus
       −        \[mi]          u2212        special variant of minus + ***
       ∓        \[-+]          u2213        minus‐plus
       ±        \[+-]          u00B1        plus‐minus + ***
       ±        \[t+-]         u00B1        text variant of \[+-]
       ⋅        \[md]          u22C5        multiplication dot
       ×        \[mu]          u00D7        multiplication sign + ***
       ×        \[tmu]         u00D7        text variant of \[mu]
       ⊗        \[c*]          u2297        circled times
       ⊕        \[c+]          u2295        circled plus
       ÷        \[di]          u00F7        division sign + ***
       ÷        \[tdi]         u00F7        text variant of \[di]
       ⁄        \[f/]          u2044        fraction slash
       *        *              u002A        asterisk
       ∗        \[**]          u2217        mathematical asterisk +

       ≤        \[<=]          u2264        less than or equal to +
       ≥        \[>=]          u2265        greater than or equal to +
       ≪        \[<<]          u226A        much less than
       ≫        \[>>]          u226B        much greater than
       =        =              u003D        equals
       =        \[eq]          u003D        special variant of equals + ***
       ≠        \[!=]          u003D_0338   not equals +
       ≡        \[==]          u2261        equivalent +
       ≢        \[ne]          u2261_0338   not equivalent
       ≅        \[=~]          u2245        approximately equal to
       ≃        \[|=]          u2243        asymptotically equal to +
       ~        \[ti]          u007E        tilde +
       ∼        \[ap]          u223C        similar to, tilde operator +
       ≈        \[~~]          u2248        almost equal to
       ≈        \[~=]          u2248        almost equal to
       ∝        \[pt]          u221D        proportional to +

       ∅        \[es]          u2205        empty set +
       ∈        \[mo]          u2208        element of a set +
       ∉        \[nm]          u2208_0338   not element of set
       ⊂        \[sb]          u2282        proper subset +
       ⊄        \[nb]          u2282_0338   not subset
       ⊃        \[sp]          u2283        proper superset +
       ⊅        \[nc]          u2283_0338   not superset
       ⊆        \[ib]          u2286        subset or equal +
       ⊇        \[ip]          u2287        superset or equal +
       ∩        \[ca]          u2229        intersection, cap +
       ∪        \[cu]          u222A        union, cup +

       ∠        \[/_]          u2220        angle
       ⊥        \[pp]          u22A5        perpendicular
       ∫        \[is]          u222B        integral +
       ∫        \[integral]    u222B        integral ***
       ∑        \[sum]         u2211        summation ***
       ∏        \[product]     u220F        product ***
       ∐        \[coproduct]   u2210        coproduct ***
       ∇        \[gr]          u2207        gradient +
       √        \[sr]          u221A        radical sign, square root +
       ‾        \[rn]          u203E        overline +
       ‾        \[radicalex]   ‐‐‐          radical extension
       √        \[sqrt]        u221A        radical sign, square root ***
       ‾        \[sqrtex]      ‐‐‐          radical extension ***

       ⌈        \[lc]          u2308        left ceiling +
       ⌉        \[rc]          u2309        right ceiling +
       ⌊        \[lf]          u230A        left floor +
       ⌋        \[rf]          u230B        right floor +

       ∞        \[if]          u221E        infinity +
       ℵ        \[Ah]          u2135        aleph symbol
       ƒ        \[Fn]          u0192        lowercase f with hook, function
       ℑ        \[Im]          u2111        blackletter I, imaginary part
       ℜ        \[Re]          u211C        blackletter R, real part
       ℘        \[wp]          u2118        Weierstrass p
       ∂        \[pd]          u2202        partial differential
       ℏ        \[-h]          u210F        h bar
       ℏ        \[hbar]        u210F        h bar

   Greek glyphs
       These glyphs are intended for technical use, not for typesetting  Greek
       language  text; normally, the uppercase letters have upright shape, and
       the lowercase ones are slanted.

       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       Α        \[*A]   u0391     uppercase alpha +
       Β        \[*B]   u0392     uppercase beta +
       Γ        \[*G]   u0393     uppercase gamma +
       Δ        \[*D]   u0394     uppercase delta +
       Ε        \[*E]   u0395     uppercase epsilon +
       Ζ        \[*Z]   u0396     uppercase zeta +
       Η        \[*Y]   u0397     uppercase eta +
       Θ        \[*H]   u0398     uppercase theta +
       Ι        \[*I]   u0399     uppercase iota +
       Κ        \[*K]   u039A     uppercase kappa +
       Λ        \[*L]   u039B     uppercase lambda +
       Μ        \[*M]   u039C     uppercase mu +
       Ν        \[*N]   u039D     uppercase nu +
       Ξ        \[*C]   u039E     uppercase xi +
       Ο        \[*O]   u039F     uppercase omicron +
       Π        \[*P]   u03A0     uppercase pi +
       Ρ        \[*R]   u03A1     uppercase rho +
       Σ        \[*S]   u03A3     uppercase sigma +
       Τ        \[*T]   u03A4     uppercase tau +
       Υ        \[*U]   u03A5     uppercase upsilon +
       Φ        \[*F]   u03A6     uppercase phi +
       Χ        \[*X]   u03A7     uppercase chi +
       Ψ        \[*Q]   u03A8     uppercase psi +
       Ω        \[*W]   u03A9     uppercase omega +

       α        \[*a]   u03B1     lowercase alpha +
       β        \[*b]   u03B2     lowercase beta +
       γ        \[*g]   u03B3     lowercase gamma +
       δ        \[*d]   u03B4     lowercase delta +
       ε        \[*e]   u03B5     lowercase epsilon +
       ζ        \[*z]   u03B6     lowercase zeta +
       η        \[*y]   u03B7     lowercase eta +
       θ        \[*h]   u03B8     lowercase theta +
       ι        \[*i]   u03B9     lowercase iota +
       κ        \[*k]   u03BA     lowercase kappa +
       λ        \[*l]   u03BB     lowercase lambda +
       μ        \[*m]   u03BC     lowercase mu +
       ν        \[*n]   u03BD     lowercase nu +
       ξ        \[*c]   u03BE     lowercase xi +
       ο        \[*o]   u03BF     lowercase omicron +
       π        \[*p]   u03C0     lowercase pi +
       ρ        \[*r]   u03C1     lowercase rho +
       σ        \[*s]   u03C3     lowercase sigma +
       τ        \[*t]   u03C4     lowercase tau +
       υ        \[*u]   u03C5     lowercase upsilon +
       ϕ        \[*f]   u03D5     lowercase phi +
       χ        \[*x]   u03C7     lowercase chi +
       ψ        \[*q]   u03C8     lowercase psi +
       ω        \[*w]   u03C9     lowercase omega +

       ϵ        \[+e]   u03F5     variant epsilon (lunate)
       ϑ        \[+h]   u03D1     variant theta (cursive form)
       ϖ        \[+p]   u03D6     variant pi (similar to omega)
       φ        \[+f]   u03C6     variant phi (curly shape)
       ς        \[ts]   u03C2     terminal lowercase sigma +

   Playing card symbols
       Output   Input   Unicode   Notes
       ────────────────────────────────────────────────────────────────────────
       ♣        \[CL]   u2663     solid club suit
       ♠        \[SP]   u2660     solid spade suit
       ♥        \[HE]   u2665     solid heart suit
       ♦        \[DI]   u2666     solid diamond suit

History
       A consideration of the typefaces originally available to AT&T nroff and
       troff illuminates many conventions that one might  regard  as  idiosyn‐
       cratic  fifty  years  afterward.  (See section “History” of roff(7) for
       more context.)  The face used by the Teletype Model 37 terminals of the
       Murray Hill Unix Room was based on ASCII, but assigned  multiple  mean‐
       ings to several code points, as suggested by that standard.  Decimal 34
       (") served as a dieresis accent and neutral double quotation mark; dec‐
       imal  39 (') as an acute accent, apostrophe, and closing (right) single
       quotation mark; decimal 45 (-) as a hyphen and a minus sign; decimal 94
       (^) as a circumflex accent and caret; decimal 96 (`) as a grave  accent
       and  opening  (left)  single  quotation  mark; and decimal 126 (~) as a
       tilde accent and (with a half‐line motion) swung dash.   The  Model  37
       bore  an optional extended character set offering upright Greek letters
       and several mathematical symbols; these were documented as early as the
       kbd(VII) man page of the (First Edition) Unix Programmer’s Manual.

       At the time Graphic Systems  delivered  the  C/A/T  phototypesetter  to
       AT&T, the ASCII character set was not considered a standard basis for a
       glyph  repertoire  by traditional typographers.  In the stock Times ro‐
       man, italic, and bold styles available, several ASCII  characters  were
       not  present  at all, nor was most of the Teletype’s extended character
       set.  AT&T commissioned a “special” font to ensure no  loss  of  reper‐
       toire.

       A  representation  of  the  coverage of the C/A/T’s text fonts follows.
       The glyph resembling an underscore is a baseline rule, and that  resem‐
       bling  a vertical line is a box rule.  In italics, the box rule was not
       slanted.  We also observe that the hyphen and minus sign  were  already
       “de‐unified”  by the fonts provided; a decision whither to map an input
       “-” therefore had to be taken.

              ┌─────────────────────────────────────────────────────┐
              │ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z │
              │ a b c d e f g h i j k l m n o p q r s t u v w x y z │
              │ 0 1 2 3 4 5 6 7 8 9 fi fl ffi ffl                   │
              │ ! $ % & ( ) ‘ ’ * + - . , / : ; = ? [ ] │           │
              │ • □ — ‐ _ ¼ ½ ¾ ° † ′ ¢ ® ©                         │
              └─────────────────────────────────────────────────────┘

       The special font supplied  the  missing  ASCII  and  Teletype  extended
       glyphs,  among  several  others.  The plus, minus, and equals signs ap‐
       peared in the special font despite availability in text fonts “to insu‐
       late the appearance of equations from the  choice  of  standard  [read:
       text] fonts”—a priority since troff was turned to the task of mathemat‐
       ical typesetting as soon as it was developed.

       We note that AT&T took the opportunity to de‐unify the apostrophe/right
       single  quotation mark from the acute accent (a choice ISO later dupli‐
       cated in its 8859 series of standards).  A slash intended to be mirror‐
       symmetric with the backslash was also included, as was the Bell  System
       logo; we do not attempt to depict the latter.

           ┌───────────────────────────────────────────────────────────┐
           │ α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ σ ς τ υ ϕ χ ψ ω         │
           │ Γ Δ Θ Λ Ξ Π Σ Υ Φ Ψ Ω                                     │
           │ " ´ \ ^ _ ` ~ / < > { } # @ + − = ∗                       │
           │ ≥ ≤ ≡ ≈ ∼ ≠ ↑ ↓ ← → × ÷ ± ∞ ∂ ∇ ¬ ∫ ∝ √ ‾ ∪ ∩ ⊂ ⊃ ⊆ ⊇ ∅ ∈ │
           │ § ‡ ☜ ☞ | ○ ⎧ ⎩ ⎫ ⎭ ⎨ ⎬ ⎪ ⌊ ⌋ ⌈ ⌉                         │
           └───────────────────────────────────────────────────────────┘

       One  ASCII  character  as rendered by the Model 37 was apparently aban‐
       doned.  That device printed decimal 124 (|) as a broken vertical  line,
       like Unicode U+00A6 (¦).  No equivalent was available on the C/A/T; the
       box rule \[br], brace vertical extension \[bv], and “or” operator \[or]
       were used as contextually appropriate.

       Devices  supported by AT&T device‐independent troff exhibited some dif‐
       ferences in glyph detail.  For example, on the Autologic  APS‐5  photo‐
       typesetter, the square \(sq became filled in the Times bold face.

Files
       The files below are loaded automatically by the default troffrc.

       /usr/share/groff/1.23.0/tmac/composite.tmac
              assigns  alternate mappings for identifiers after the first in a
              composite special character  escape  sequence.   See  subsection
              “Accents” above.

       /usr/share/groff/1.23.0/tmac/fallbacks.tmac
              defines  fallback  mappings  for Unicode code points such as the
              increment sign (U+2206) and upper‐ and lowercase Roman numerals.

Authors
       This document was written by James Clark ⟨jjc@jclark.com⟩,  with  addi‐
       tions  by  Werner  Lemberg  ⟨wl@gnu.org⟩  and Bernd Warken ⟨groff-bernd
       .warken-72@web.de⟩, revised to use tbl(1)  by  Eric  S.  Raymond  ⟨esr@
       thyrsus.com⟩,  and  largely rewritten by G. Branden Robinson ⟨g.branden
       .robinson@gmail.com⟩.

See also
       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is  the primary groff manual.  Section “Using Symbols” may be
       of particular  note.   You  can  browse  it  interactively  with  “info
       '(groff) Using Symbols'”.

       “An extension to the troff character set for Europe”, E.G. Keizer, K.J.
       Simonsen, J. Akkerhuis; EUUG Newsletter, Volume 9, No. 2, Summer 1989

       The Unicode Standard ⟨http://www.unicode.org⟩

       “7‐bit  Character Sets” ⟨https://www.aivosto.com/articles/charsets-7bit
       .html⟩ by Tuomas Salste documents the inherent  ambiguity  and  config‐
       urable code points of the ASCII encoding standard.

       “Nroff/Troff User’s Manual” by Joseph F. Ossanna, 1976, AT&T Bell Labo‐
       ratories Computing Science Technical Report No. 54, features two tables
       that throw light on the glyph repertoire available to “typesetter roff”
       when  it  was first written.  Be careful of re‐typeset versions of this
       document that can be found on the Internet.   Some  do  not  accurately
       represent  the original document: several glyphs are obviously missing.
       More subtly, lowercase Greek letters are rendered upright, not  slanted
       as  they  appeared in the C/A/T’s special font and as expected by troff
       users.

       groff_rfc1345(7) describes an  alternative  set  of  special  character
       glyph  names, which extends and in some cases overrides the definitions
       listed above.

       groff(1), troff(1), groff(7)

groff 1.23.0                      2 July 2023                    groff_char(7)
───────────────────────────────────────────────────────────────────────────────
groff_diff(7)          Miscellaneous Information Manual          groff_diff(7)

Name
       groff_diff - differences between GNU roff and AT&T troff

Description
       The GNU roff text processing system, groff, is  an  extension  of  AT&T
       troff, the typesetting system originating in Unix systems of the 1970s.
       groff removes many arbitrary limitations and adds features, both to the
       input language and to the page description language output by the troff
       formatter.   Differences  arising  from  groff’s implementation of AT&T
       troff features are also noted.  See roff(7) for background.

Language
       GNU troff features identifiers of arbitrary length; supports color out‐
       put, non‐integral type sizes, and user‐defined  characters;  adds  more
       conditional  expression  operators; recognizes additional scaling units
       and numeric operators; enables  general  file  I/O  (in  “unsafe  mode”
       only); and exposes more formatter state.

   Long names
       GNU  troff introduces many new requests; with three exceptions (cp, do,
       rj), they have names longer than two characters.  The names  of  regis‐
       ters,  fonts,  strings/macros/diversions, environments, special charac‐
       ters, streams, and colors can be of any length.   Anywhere  AT&T  troff
       supports a parameterized escape sequence that uses an opening parenthe‐
       sis “(” to introduce a two‐character argument, groff supports a square‐
       bracketed  form  “[]”  where  the  argument  within can be of arbitrary
       length.

   Font families, abstract styles, and translation
       GNU troff can group text typefaces into families containing each of the
       styles “R”, “I”, “B”, and “BI”.  So that a document need not be coupled
       to a specific font family, an output device can associate  a  style  in
       the  abstract  sense with a mounting position.  Thus the default family
       can be combined with a style dynamically,  producing  a  resolved  font
       name.  A document can translate, or remap, fonts with the ftr request.

       Applying the requests cs, bd, tkf, uf, or fspecial to an abstract style
       affects  the  member of the default family corresponding to that style.
       The default family can be set with the fam request or  -f  command‐line
       option.  The styles directive in the output device’s DESC file controls
       which  mounting  positions  (if  any) are initially associated with ab‐
       stract styles rather than fonts, and the sty request  can  update  this
       association.

   Colors
       groff supports color output with a variety of color spaces and up to 16
       bits  per  channel.   Some devices, particularly terminals, may be more
       limited.  When color support is enabled, two colors are current at  any
       given  time:  the  stroke  color, with which glyphs, rules (lines), and
       geometric figures are drawn, and the fill color, which paints the inte‐
       rior of filled geometric figures.  The  color,  defcolor,  gcolor,  and
       fcolor  requests;  \m  and  \M escape sequences; and .color, .m, and .M
       registers exercise color support.

   Fractional type sizes and new scaling units
       AT&T troff interpreted all type size measurements in points.   Combined
       with  integer arithmetic, this design choice made it impossible to sup‐
       port, for instance, ten and a half‐point type.  In GNU troff, an output
       device can select a scaling factor that subdivides a point into “scaled
       points”.  A type size expressed in scaled points can thus  represent  a
       non‐integral type size.

       A scaled point is equal to 1/sizescale points, where sizescale is spec‐
       ified  in  the  device  description  file, DESC, and defaults to 1; see
       groff_font(5).  Requests and escape sequences in  GNU  troff  interpret
       arguments  that  represent  a  type size in points, which the formatter
       multiplies by sizescale and converts to an integer.  Arguments  treated
       in  this  way  comprise those to the escape sequences \H and \s, to the
       request ps, the third argument to the cs request, and  the  second  and
       fourth  arguments  to  the tkf request.  Scaled points may be specified
       explicitly with the z scaling unit.  In GNU troff, the register  \n[.s]
       can  interpolate a non‐integral type size.  The register \n[.ps] inter‐
       polates the type size in scaled points.

       For example, if sizescale is 1000, then a scaled  point  is  one  thou‐
       sandth  of  a  point.  Consequently, “.ps 10.5” is synonymous with “.ps
       10.5z”; both set the type size to 10,500 scaled points, or 10.5 points.

       It makes no sense to use the “z” scaling unit in a  numeric  expression
       whose  default scaling unit is neither “u” nor “z”, so GNU troff disal‐
       lows this.  Similarly, it is nonsensical to use a  scaling  unit  other
       than  “z”  or  “u”  in  a numeric expression whose default scaling unit
       is “z”, so GNU troff disallows this as well.

       Another new scaling unit, “s”, multiplies by the number of basic  units
       in  a  scaled  point.  Thus, “\n[.ps]s” is equal to “1m” by definition.
       Do not confuse the “s” and “z” scaling units.

       Output devices may be limited in the type sizes they can  employ.   The
       .s  and .ps registers represent the type size as selected by the output
       driver as it understands a device’s  capability.   The  last  requested
       type  size  is  interpolated in scaled points by the read‐only register
       .psr and in points as a decimal fraction by the read‐only string‐valued
       register .sr.  Both are associated with the environment.  For  example,
       if  a type size of 10.95 points is requested, and the nearest size per‐
       mitted by a sizes request (or by the sizes or sizescale  directives  in
       the device’s DESC file) is 11 points, the output driver uses the latter
       value.

       A  further  two new measurement units available in groff are “M”, which
       indicates hundredths of an em, and “f”,  which  multiplies  by  65,536.
       The latter provides convenient fractions for color definitions with the
       defcolor request.  For example, 0.5f equals 32768u.

   Numeric expressions
       GNU  troff  permits  spaces in a numeric expression within parentheses,
       and offers three new operators.

       e1>?e2 Interpolate the greater of e1 and e2.

       e1<?e2 Interpolate the lesser of e1 and e2.

       (c;e)  Evaluate e using c as the default scaling unit, ignoring scaling
              units in e if c is empty.

   Conditional expressions
       More conditions can be tested with the “if” and ie requests, as well as
       the new “while” request.

       c chr  True if a character chr is available, where chr is  an  ordinary
              character  (Unicode basic Latin excluding control characters and
              the space), a special character, or \N'index'.

       d nam  True if a string, macro, diversion, or request nam is defined.

       F fnt  True if a font fnt is available; fnt can be an abstract style or
              a font name.  fnt is handled as if it were accessed with the  ft
              request  (that  is, abstract styles and font translation are ap‐
              plied), but fnt cannot be a mounting position, and  no  font  is
              mounted.

       m col  True if a color col is defined.

       r reg  True if a register reg is defined.

       S sty  True if a style sty is registered.  Font translation applies.

       v      Always  false.  This condition is for compatibility with certain
              other troff implementations only.  (This  refers  to  vtroff,  a
              translator  that  would convert the C/A/T output from early‐vin‐
              tage AT&T troff to a form suitable for Versatec and  Benson‐Var‐
              ian plotters.)

   Drawing commands
       GNU  troff  offers  drawing  commands  to create filled circles and el‐
       lipses, and polygons.  Stroked (outlined) objects are  drawn  with  the
       stroke color and filled (solid) ones shaded with the fill color.  These
       are  independent  properties; if you want a filled, stroked figure, you
       must draw the same figure twice using each drawing command.   A  filled
       figure is always smaller than a stroked one because the former is drawn
       only  within  its  defined  area, whereas strokes have a line thickness
       (set with another new drawing command, \D't').

   Escape sequences
       groff introduces several new escape sequences and extends the syntax of
       a few AT&T troff escape sequences (namely, \D, \f, \k, \n, \s, \$,  and
       \*).   In  the following list, escape sequences are collated alphabeti‐
       cally at first, and then by symbol roughly in Unicode code point order.

       \A'anything'
              Interpolate 1 if anything is a valid identifier,  and  0  other‐
              wise.   Because  invalid  input  characters are removed, invalid
              identifiers are empty or contain spaces, tabs, or newlines.  You
              can employ \A to validate a macro argument before  using  it  to
              construct another escape sequence or identifier.

       \B'anything'
              Interpolate  1  if anything is a valid numeric expression, and 0
              otherwise.  You might use \B along with the “if” request to fil‐
              ter out invalid macro arguments.

       \D'C d'
              Draw filled circle of diameter d with its leftmost point at  the
              drawing position.

       \D'E h v'
              Draw  filled  ellipse  with h and v as the axes and the leftmost
              point at the drawing position.

       \D'p h1 v1 ... hn vn'
              Draw polygon with vertices at drawing position and each point in
              sequence.  GNU troff closes the polygon by drawing a  line  from
              (hn,  vn) back to the initial drawing position; DWB and Heirloom
              troffs do not.  Afterward,  the  drawing  position  is  left  at
              (hn, vn).

       \D'P h1 v1 ... hn vn'
              As \D'p', but the polygon is filled.

       \D't n'
              Set  line thickness of geometric objects to to n basic units.  A
              zero n selects the minimal supported thickness.   A  negative  n
              selects  a  thickness proportional to the type size; this is the
              default.

       \E     Embed an escape character that is not interpreted in  copy  mode
              (compare with \a and \t).  You can use it to ease the writing of
              nested  macro  definitions.   It  is  also  convenient to define
              strings containing escape sequences that need to work when  used
              in copy mode (for example, as macro arguments), or which will be
              interpolated at varying macro nesting depths.

       \f[font]
              Select  font,  which may be a mounting position, abstract style,
              or font name, to choose the typeface.  \f[]  and  \fP  are  syn‐
              onyms; we recommend the former.

       \Ff
       \F(fm
       \F[family]
              Select default font family.  \F[] makes the previous font family
              the  default.   \FP is unlike \fP; it selects font family “P” as
              the default.  See the fam request below.

       \k(rg
       \k[reg]
              Mark  horizontal  drawing  position  in  two‐character  register
              name rg or arbitrary register name reg.

       \mc
       \m(cl
       \m[col]
              Set  the stroke color.  \m[] restores the previous stroke color,
              or the default if there is none.

       \Mc
       \M(cl
       \M[col]
              Set the fill color.  \M[] restores the previous fill  color,  or
              the default if there is none.

       \n[reg]
              Interpolate register reg.

       \On
       \O[n]  Suppress  troff output of glyphs and geometric objects.  The se‐
              quences \O2, \O3, \O4, and \O5 are intended for internal use  by
              grohtml(1).

              \O0
              \O1    Disable  and enable, respectively, the emission of glyphs
                     and geometric objects to the output driver, provided that
                     this sequence occurs at the outermost  suppression  level
                     (see  \O3  and \O4).  Horizontal motions corresponding to
                     non‐overstruck glyph widths still occur.  These sequences
                     also reset the registers opminx, opminy, opmaxx, and  op‐
                     maxy  to  -1.  These four registers mark the top left and
                     bottom right hand corners of a box encompassing all writ‐
                     ten or drawn output.

              \O2    At the outermost suppression level,  enable  emission  of
                     glyphs  and  geometric objects, and write to the standard
                     error stream the page  number  and  values  of  the  four
                     aforementioned   registers  encompassing  glyphs  written
                     since the last interpolation of a \O sequence, as well as
                     the page offset, line length, image file name  (if  any),
                     horizontal  and  vertical device motion quanta, and input
                     file name.  Numeric values are in basic units.

              \O3
              \O4    Begin and end a nested suppression  level,  respectively.
                     grohtml  uses  this  mechanism to create images of output
                     preprocessed with pic, eqn, and tbl.  At  startup,  troff
                     is  at the outermost suppression level.  pre-grohtml gen‐
                     erates these sequences when processing the document,  us‐
                     ing troff with the ps output device, Ghostscript, and the
                     PNM  tools  to  produce  images in PNG format.  These se‐
                     quences start a new page if the device  is  not  html  or
                     xhtml,  to  reduce  the  number of images crossing a page
                     boundary.

              \O5[Pfile]
                     At the outermost suppression level, write the  name  file
                     to the standard error stream at position P, which must be
                     one  of l, r, c, or i, corresponding to left, right, cen‐
                     tered, and inline alignments within the document, respec‐
                     tively.  file is is a name associated with the production
                     of the next image.

       \R'name ±n'
              Synonymous with “.nr name ±n”.

       \s[±n]
       \s±[n]
       \s'±n'
       \s±'n' Set the type size to, or increment or decrement it by, n  scaled
              points.

       \Ve
       \V(ev
       \V[env]
              Interpolate  contents  of  the  environment variable env, as re‐
              turned by getenv(3).  \V is interpreted even in copy mode.

       \X'anything'
              Within \X arguments, the escape sequences \&, \), \%, and \: are
              ignored; \space and \~ are converted to single space characters;
              and \\ is reduced to \.  So that the basic Latin subset  of  the
              Unicode  character set (that is, ISO 646:1991‐IRV or, popularly,
              “US‐ASCII”) can be reliably encoded  in  anything,  the  special
              character  escape  sequences  \-,  \[aq],  \[dq],  \[ga], \[ha],
              \[rs], and \[ti] are  mapped  to  basic  Latin  characters;  see
              groff_char(7).   For this transformation, character translations
              and definitions are ignored.  Other  escape  sequences  are  not
              supported.

              If  the use_charnames_in_special directive appears in the output
              device’s DESC file, the use  of  special  character  escape  se‐
              quences  is  not an error; they are simply output verbatim (with
              the exception of the seven mapped to Unicode basic Latin charac‐
              ters, discussed above).  use_charnames_in_special  is  currently
              employed only by grohtml(1).

       \Ym
       \Y(ma
       \Y[mac]
              Interpolate  a macro as a device control command.  This is simi‐
              lar to \X'\*[mac]', except the contents of mac  are  not  inter‐
              preted,  and  mac  can  be  a  macro  and thus contain newlines,
              whereas the argument to \X cannot.  This inclusion  of  newlines
              requires  an extension to the AT&T troff output format, and will
              confuse postprocessors that do not know about it.

       \Z'anything'
              Save the drawing position, format  anything,  then  restore  it.
              Tabs and leaders in the argument are ignored with an error diag‐
              nostic.

       \#     Everything  up  to  and  including  the next newline is ignored.
              This escape sequence is interpreted even in copy  mode.   \#  is
              like  \",  except  that \" does not ignore a newline; the latter
              therefore cannot be used by itself for a  whole‐line  comment—it
              leaves a blank line on the input stream.

       \$0    Interpolate  the  name  by which the macro being interpreted was
              called.  In GNU troff this name can vary; see the als request.

       \$(nn
       \$[nnn]
              In a macro or string definition, interpolate the nnth  or  nnnth
              argument.   Macros  and  strings can have an unlimited number of
              arguments.

       \$*    In a macro or string definition, interpolate the  catenation  of
              all arguments, separated by spaces.

       \$@    In  a  macro or string definition, interpolate the catenation of
              all arguments, with each surrounded by double quotes  and  sepa‐
              rated by spaces.

       \$^    In  a  macro or string definition, interpolate the catenation of
              all arguments constructed in a form suitable for passage to  the
              ds request.

       \)     Interpolate a transparent dummy character—one that is ignored by
              end‐of‐sentence  detection.  It behaves as \&, except that \& is
              treated as letters and numerals normally are after “.”, “?”, and
              “!”; \& cancels end‐of‐sentence detection, and \) does not.

       \*[string [arg ...]]
              Interpolate string, passing it arg ... as arguments.

       \/     Apply an italic correction: modify the spacing of the  preceding
              glyph so that the distance between it and the following glyph is
              correct  if  the latter is of upright shape.  For example, if an
              italic “f” is followed immediately by a roman right parenthesis,
              then in many fonts the top right portion of the “f” overlaps the
              top left of the right parenthesis, which is ugly.  Inserting  \/
              between  them  avoids  this  problem.   Use this escape sequence
              whenever an oblique glyph is immediately followed by an  upright
              glyph without any intervening space.

       \,     Apply  a  left italic correction: modify the spacing of the fol‐
              lowing glyph so that the distance between it and  the  preceding
              glyph  is  correct if the latter is of upright shape.  For exam‐
              ple, if a roman left parenthesis is immediately followed  by  an
              italic  “f”,  then  in  many  fonts  the  bottom left portion of
              the “f” overlaps the bottom of the left  parenthesis,  which  is
              ugly.   Inserting \, between them avoids this problem.  Use this
              escape sequence whenever an upright glyph  is  followed  immedi‐
              ately by an oblique glyph without any intervening space.

       \:     Insert  a  non‐printing  break point.  That is, a word can break
              there, but the soft hyphen character does  not  mark  the  break
              point if it does (in contrast to “\%”).  This escape sequence is
              an  input word boundary, so the remainder of the word is subject
              to hyphenation as normal.

       \?anything\?
              When used in a diversion, this transparently embeds anything  in
              the  diversion.  anything is read in copy mode.  When the diver‐
              sion is reread, anything is interpreted.  anything may not  con‐
              tain  newlines; use \! if you want to embed newlines in a diver‐
              sion.  The escape sequence \? is also recognized  in  copy  mode
              and  becomes  an  internal code; it is this code that terminates
              anything.  Thus

                     .nr x 1
                     .nf
                     .di d
                     \?\\?\\\\?\\\\\\\\nx\\\\?\\?\?
                     .di
                     .nr x 2
                     .di e
                     .d
                     .di
                     .nr x 3
                     .di f
                     .e
                     .di
                     .nr x 4
                     .f

              prints 4.

       \[char]
              Typeset the special character char.

       \[base‐char combining‐component ...]
              Typeset a composite glyph consisting of base‐char overlaid  with
              one  or  more combining‐components.  For example, “\[A ho]” is a
              capital letter “A” with  a  “hook  accent”  (ogonek).   See  the
              composite request below; Groff: The GNU Implementation of troff,
              the  groff  Texinfo  manual, for details of composite glyph name
              construction; and groff_char(7) for a list of components used in
              composite glyph names.

       \~     Insert an unbreakable space that is adjustable like an  ordinary
              space.   It  is  discarded  from  the end of an output line if a
              break is forced.

   Restricted requests
       To mitigate risks from untrusted input documents, the  pi  and  sy  re‐
       quests  are disabled by default.  troff(1)’s -U option enables the for‐
       matter’s “unsafe mode”, restoring their function  (and  enabling  addi‐
       tional groff extension requests, open, opena, and pso).

   New requests
       .aln new old
              Create  alias  new  for existing register named old, causing the
              names to refer to the same stored value.  If old is undefined, a
              warning in category “reg” is generated and the  request  is  ig‐
              nored.   To  remove  a register alias, invoke rr on its name.  A
              register’s contents do not become inaccessible until it  has  no
              more names.

       .als new old
              Create  alias new for existing request, string, macro, or diver‐
              sion named old, causing the names to refer to  the  same  stored
              object.   If  old  is  undefined, a warning in category “mac” is
              produced, and the request is ignored.  The “am”, “as”,  da,  de,
              di,  and ds requests (together with their variants) create a new
              object only if the name of the macro, diversion,  or  string  is
              currently  undefined or if it is defined as a request; normally,
              they modify the value of  an  existing  object.   To  remove  an
              alias,  invoke  rm  on  its  name.  The object itself is not de‐
              stroyed until it has no more names.

              When a request, macro, string, or diversion is aliased, redefin‐
              itions and appendments “write through” alias names.  To  replace
              an  alias  with a separately defined object, you must use the rm
              request on its name first.

       .am1 name [end‐name]
              As “am”, but compatibility mode is disabled while the appendment
              to name is interpreted: a “compatibility save” token is inserted
              at its beginning, and a “compatibility  restore”  token  at  its
              end.   As a consequence, the requests “am”, am1, de, and de1 can
              be intermixed freely since the compatibility save/restore tokens
              affect only the parts of the macro populated by am1 and de1.

       .ami name [end‐name]
              Append to macro indirectly.  See dei below.

       .ami1 name [end‐name]
              As ami, but compatibility mode is disabled during interpretation
              of the appendment.

       .as1 name [contents]
              As “as”, but compatibility mode is disabled while the appendment
              to name is interpreted: a “compatibility save” token is inserted
              at the beginning of contents, and a “compatibility restore”  to‐
              ken after it.  As a consequence, the requests “as”, as1, ds, and
              ds1  can  be  intermixed freely since the compatibility save/re‐
              store tokens affect only the portions of the  strings  populated
              by as1 and ds1.

       .asciify div
              Unformat  the  diversion  div  in  a way such that Unicode basic
              Latin (ASCII) characters, characters translated  with  the  trin
              request,  space characters, and some escape sequences, that were
              formatted in the diversion div are treated like  ordinary  input
              characters  when  div is reread.  Doing so can be useful in con‐
              junction with the writem request.  asciify can be also used  for
              gross hacks; for example, the following sets register n to 1.

                     .tr @.
                     .di x
                     @nr n 1
                     .br
                     .di
                     .tr @@
                     .asciify x
                     .x

              asciify  cannot  return all items in a diversion to their source
              equivalent: nodes such as those produced by \N[...] will  remain
              nodes,  so  the result cannot be guaranteed to be a pure string.
              See section “Copy mode” in groff(7).  Glyph parameters  such  as
              the  type  face  and  size  are  not  preserved; use unformat to
              achieve that.

       .backtrace
              Write backtrace of input stack to  the  standard  error  stream.
              See the -b option of troff(1).

       .blm [name]
              Set  a  blank  line macro (trap).  If a blank line macro is thus
              defined, groff executes macro when a blank line  is  encountered
              in  the  input file, instead of the usual behavior.  A line con‐
              sisting only of spaces is also treated as blank and  subject  to
              this  trap.   If no argument is supplied, the default blank line
              behavior is (re‐)established.

       .box [name]
       .boxa [name]
              Divert (or append) output to name, similarly to the  di  and  da
              requests, respectively.  Any pending output line is not included
              in  the  diversion.  Without an argument, stop diverting output;
              any pending output line inside the diversion is discarded.

       .break Exit a “while” loop.  Do not confuse this request with  a  typo‐
              graphical break or the br request.  See “continue”.

       .brp   Break and adjust line; this is the AT&T troff escape sequence \p
              in request form.

       .cflags n c1 c2 ...
              Assign  properties encoded by the number n to characters c1, c2,
              and so on.  Ordinary and special characters have certain associ‐
              ated properties.  (Glyphs don’t: to GNU troff, like AT&T device‐
              independent troff, a glyph is an identifier corresponding  to  a
              rectangle  with some metrics; see groff_font(5).)  The first ar‐
              gument is the sum of the desired flags and the  remaining  argu‐
              ments  are  the  characters  to  be  assigned  those properties.
              Spaces between the cn arguments are optional.  Any  argument  cn
              can  be  a character class defined with the class request rather
              than an individual character.

              The non‐negative integer n is the sum of any of  the  following.
              Some combinations are nonsensical, such as “33” (1 + 32).

              1      Recognize  the character as ending a sentence if followed
                     by a newline or two spaces.  Initially, characters  “.?!”
                     have this property.

              2      Enable breaks before the character.  A line is not broken
                     at  a  character with this property unless the characters
                     on each side both have non‐zero hyphenation codes.   This
                     exception  can be overridden by adding 64.  Initially, no
                     characters have this property.

              4      Enable breaks after the character.  A line is not  broken
                     at  a  character with this property unless the characters
                     on each side both have non‐zero hyphenation codes.   This
                     exception  can  be  overridden  by adding 64.  Initially,
                     characters “-\[hy]\[em]” have this property.

              8      Mark the glyph associated with this character as overlap‐
                     ping other instances of itself horizontally.   Initially,
                     characters   “\[ul]\[rn]\[ru]\[radicalex]\[sqrtex]”  have
                     this property.

              16     Mark the glyph associated with this character as overlap‐
                     ping other instances of  itself  vertically.   Initially,
                     the character “\[br]” has this property.

              32     Mark the character as transparent for the purpose of end‐
                     of‐sentence  recognition.  In other words, an end‐of‐sen‐
                     tence character followed by any number of characters with
                     this property is treated as the end of a sentence if fol‐
                     lowed by a newline or two spaces.  This is  the  same  as
                     having a zero space factor in TeX.  Initially, characters
                     “'")]*\[dg]\[dd]\[rq]\[cq]” have this property.

              64     Ignore  hyphenation  codes of the surrounding characters.
                     Use this value in combination with values 2 and 4.   Ini‐
                     tially, no characters have this property.

                     For  example,  if you need an automatic break point after
                     the en‐dash in numeric ranges like “3000–5000”, insert
                            .cflags 68 \[en]
                     into your document.  However, this can lead to bad layout
                     if done without thinking; in most  situations,  a  better
                     solution than changing the cflags value is inserting “\:”
                     right  after  the hyphen at the places that really need a
                     break point.

              The remaining values were implemented for  East  Asian  language
              support; those who use alphabetic scripts exclusively can disre‐
              gard them.

              128    Prohibit  a break before the character, but allow a break
                     after the character.  This works only in combination with
                     values 256 and 512 and has  no  effect  otherwise.   Ini‐
                     tially, no characters have this property.

              256    Prohibit  a  break after the character, but allow a break
                     before the character.  This  works  only  in  combination
                     with  values  128  and  512  and has no effect otherwise.
                     Initially, no characters have this property.

              512    Allow a break before or after the character.  This  works
                     only  in  combination  with values 128 and 256 and has no
                     effect otherwise.  Initially,  no  characters  have  this
                     property.

              In contrast to values 2 and 4, the values 128, 256, and 512 work
              pairwise.   If,  for  example, the left character has value 512,
              and the right character 128, no break will be automatically  in‐
              serted  between  them.   If  we use value 6 instead for the left
              character, a break after the character can’t be suppressed since
              the neighboring character on the right doesn’t get examined.

       .char c contents
              Define the ordinary or special character c  as  contents,  which
              can  be  empty.  More precisely, char defines a groff object (or
              redefines an existing one) that is accessed with the name  c  on
              input,  and  produces contents on output.  Every time c is to be
              formatted, contents is processed in a temporary environment  and
              the  result  is  wrapped up into a single object.  Compatibility
              mode is turned off and the escape character is set  to  \  while
              contents  is  processed.   Any emboldening, constant spacing, or
              track kerning is applied to this object as a whole, not to  each
              character in contents.

              An  object defined by this request can be used just like a glyph
              provided by the output device.  In particular, other  characters
              can  be translated to it with the tr request; it can be made the
              tab or leader fill character with the tc and  lc  requests;  se‐
              quences  of it can be drawn with the \l and \L escape sequences;
              and, if the hcode request is used on c, it is subject  to  auto‐
              matic hyphenation.

              To  prevent  infinite recursion, occurrences of c within its own
              definition are treated normally (as if it were not being defined
              with char).  The tr and trin requests take  precedence  if  char
              both apply to c.  A character definition can be removed with the
              rchar request.

       .chop object
              Remove  the  last character from the macro, string, or diversion
              object.  This is useful for removing the newline from the end of
              a diversion that is to be interpolated as a  string.   This  re‐
              quest  can  be  used  repeatedly on the same object; see section
              “gtroff Internals” in Groff: The GNU  Implementation  of  troff,
              the  groff  Texinfo  manual, for discussion of nodes inserted by
              groff.

       .class name c1 c2 ...
              Define a character class (or simply “class”) name comprising the
              characters or range expressions c1, c2, and so on.

              A class thus defined can then be referred to in lieu of  listing
              all  the  characters  within it.  Currently, only the cflags re‐
              quest can handle references to character classes.

              In the request’s simplest form, each cn is a character (or  spe‐
              cial character).
                     .class [quotes] ' \[aq] \[dq] \[oq] \[cq] \[lq] \[rq]

              Since  class  and  special  character  names share the same name
              space, we recommend starting and ending the class name with  “[”
              and “]”, respectively, to avoid collisions with existing charac‐
              ter  names  defined  by groff or the user (with char and related
              requests).  This practice applies the presence  of  “]”  in  the
              class  name to prevent the usage of the special character escape
              form “\[...]”, thus you must use the \C escape to access a class
              with such a name.

              You can also use a character range expression  consisting  of  a
              start  character followed by “-” and then an end character.  In‐
              ternally, GNU troff converts these two character names  to  Uni‐
              code  code  points  (according  to  the groff glyph list [GGL]),
              which determine the start and end values of the range.  If  that
              fails,  the  class  definition is skipped.  Furthermore, classes
              can be nested.
                     .class [prepunct] , : ; > }
                     .class [prepunctx] \C'[prepunct]' \[u2013]-\[u2016]
              The class “[prepunctx]” thus contains the contents of the  class
              “[prepunct]” and characters in the range U+2013–U+2016.

              If  you  want  to  include  “-” in a class, it must be the first
              character value in the argument list, otherwise it  gets  misin‐
              terpreted as part of the range syntax.

              It is not possible to use class names as end points of range de‐
              finitions.

              A  typical  use of the class request is to control line‐breaking
              and hyphenation rules as defined by the cflags request.  For ex‐
              ample, to inhibit line breaks before the characters belonging to
              the “[prepunctx]” class defined in the previous example, you can
              write the following.
                     .cflags 2 \C'[prepunctx]'

       .close stream
              Close the stream named stream, invalidating it as an argument to
              the write request.  See open.

       .composite c1 c2
              Map character name c1 to character name c2 when c1 is a  combin‐
              ing  component  in  a composite glyph.  Typically, this remaps a
              spacing glyph to a combining one.

       .continue
              Skip the remainder of a “while” loop’s body, immediately  start‐
              ing the next iteration.  See break.

       .color n
              If n is non‐zero or missing, enable colors (the default), other‐
              wise disable them.

       .cp n  If  n  is non‐zero or missing, enable compatibility mode, other‐
              wise disable it.  In compatibility mode, long names are not rec‐
              ognized, and the incompatibilities they cause do not arise.

       .defcolor ident scheme color‐component ...
              Define a color named ident.  scheme identifies a color space and
              determines the number of required color‐components; it  must  be
              one  of  “rgb”  (three  components),  “cmy”  (three components),
              “cmyk” (four components), or “gray” (one component).  “grey”  is
              accepted  as  a  synonym of “gray”.  The color components can be
              encoded as a hexadecimal value starting with # or ##.  The  for‐
              mer  indicates that each component is in the range 0–255 (0–FF),
              the latter the  range  0–65535  (0–FFFF).   Alternatively,  each
              color  component  can  be specified as a decimal fraction in the
              range 0–1, interpreted using a  default  scaling  unit  of  “f”,
              which multiplies its value by 65,536 (but clamps it at 65,535).

              Each  output device has a color named “default”, which cannot be
              redefined.  A device’s default stroke and fill  colors  are  not
              necessarily the same.

       .de1 name [end‐name]
              Define  a  macro  to be interpreted with compatibility mode dis‐
              abled.  When name is called, compatibility mode enablement  sta‐
              tus is saved; it is restored when the call completes.

       .dei name [end‐name]
              Define  macro  indirectly,  with the name of the macro to be de‐
              fined in string name and the name of the end  macro  terminating
              its definition in string end‐name.

       .dei1 name [end‐name]
              As  dei, but compatibility mode is disabled while the definition
              of the macro named in string name is interpreted.

       .device anything
              Write anything, read in copy mode, to troff output as  a  device
              control command.  An initial neutral double quote is stripped to
              allow the embedding of leading spaces.

       .devicem name
              Write  contents of macro or string name to troff output as a de‐
              vice control command.

       .do name [arg ...]
              Interpret the string, request, diversion, or macro  name  (along
              with  any arguments) with compatibility mode disabled.  Compati‐
              bility mode is restored (only if it was active) when the  expan‐
              sion of name is interpreted; that is, the restored compatibility
              state applies to the contents of the macro, string, or diversion
              name  as well as data read from files or pipes if name is any of
              the so, soquiet, mso, msoquiet, or pso requests.

              For example,
                     .de mac1
                     FOO
                     ..
                     .de1 mac2
                     groff
                     .mac1
                     ..
                     .de mac3
                     compatibility
                     .mac1
                     ..
                     .de ma
                     \\$1
                     ..
                     .cp 1
                     .do mac1
                     .do mac2 \" mac2, defined with .de1, calls "mac1"
                     .do mac3 \" mac3 calls "ma" with argument "c1"
                     .do mac3 \[ti] \" groff syntax accepted in .do arguments
              results in
                     FOO groff FOO compatibility c1 ~
              as output.

       .ds1 name contents
              As ds, but compatibility mode is disabled while name  is  inter‐
              preted:  a  “compatibility save” token is inserted at the begin‐
              ning of contents, and a “compatibility restore” token after it.

       .ecr   Restore the escape character saved with ecs, or set escape char‐
              acter to “\” if none has been saved.

       .ecs   Save the current escape character.

       .evc env
              Copy the properties of environment env to the  current  environ‐
              ment, except for the following data.

              • a partially collected line, if present;

              • the interruption status of the previous input line (due to use
                of the \c escape sequence);

              • the  count  of remaining lines to center, to right‐justify, or
                to underline (with or without underlined spaces)—these are set
                to zero;

              • the activation status of temporary indentation;

              • input traps and their associated data;

              • the activation status of line numbering (which can be  reacti‐
                vated with “.nm +0”); and

              • the count of consecutive hyphenated lines (set to zero).

       .fam [family]
              Set default font family to family.  If no argument is given, the
              previous  font  family  is  selected, or the formatter’s default
              family if there is none.  The formatter’s default font family is
              “T” (Times), but it can be overridden by the  output  device—see
              groff_font(5).   The  default font family is associated with the
              environment.  See \F.

       .fchar c contents
              Define fallback character c as contents.  The syntax of this re‐
              quest is the same as the char request; the difference is that  a
              character  defined with char hides a glyph with the same name in
              the selected font, whereas characters  defined  with  fchar  are
              checked  only  if c isn’t found in the selected font.  This test
              happens before special fonts are searched.

       .fcolor color
              Set the fill color to color.  Without an argument, the  previous
              fill color is selected.

       .fschar f c contents
              Define  fallback  special character c for font f as contents.  A
              character defined by fschar is located after the list  of  fonts
              declared  with  fspecial  is  searched but before those declared
              with the “special” request.

       .fspecial f s1 s2 ...
              When font f is selected, fonts s1, s2, ... are treated  as  spe‐
              cial; that is, they are searched for glyphs not found in f.  Any
              fonts  specified in the “special” request are searched after s1,
              s2, and so on.  Without s arguments, fspecial clears the list of
              fonts treated as special when f is selected.

       .ftr f g
              Translate font f to g.  Whenever a font named f is  referred  to
              in  an \f escape sequence, in the F and S conditional expression
              operators, or in the ft, ul, bd, cs, tkf, special, fspecial, fp,
              or sty requests, font g is used.  If g is missing  or  identical
              to f, then font f is not translated.

       .fzoom f zoom
              Set zoom factor zoom for font f.  zoom must a non‐negative inte‐
              ger multiple of 1/1000th.  If it is missing or is equal to zero,
              it means the same as 1000, namely no magnification.  f must be a
              resolved font name, not an abstract style.

       .gcolor color
              Set  the stroke color to color.  Without an argument, the previ‐
              ous stroke color is selected.

       .hcode c1 code1 [c2 code2] ...
              Set the hyphenation code of character c1 to code1, that of c2 to
              code2, and so on.  A hyphenation code must be an ordinary  char‐
              acter  (not  a  special  character escape sequence) other than a
              digit.  The request is ignored if given no arguments.

              For hyphenation to work, hyphenation codes must be set  up.   At
              startup,  groff  assigns  hyphenation codes to the letters “a–z”
              (mapped to themselves), to the letters “A–Z” (mapped to  “a–z”),
              and  zero  to  all other characters.  Normally, hyphenation pat‐
              terns contain only lowercase letters which should be applied re‐
              gardless of case.  In other words, they assume  that  the  words
              “ABBOT”  and “Abbot” should be hyphenated exactly as “abbot” is.
              hcode extends this principle to letters outside the Unicode  ba‐
              sic  Latin  alphabet;  without it, words containing such letters
              won’t be hyphenated properly even if the  corresponding  hyphen‐
              ation patterns contain them.

       .hla lang
              Set  the  hyphenation  language to lang.  Hyphenation exceptions
              specified with the hw request and hyphenation patterns  and  ex‐
              ceptions specified with the hpf and hpfa requests are associated
              with  the  hyphenation language.  The hla request is usually in‐
              voked by a localization file, which is in  turn  loaded  by  the
              troffrc or troffrc-end file; see the hpf request below.  The hy‐
              phenation language is associated with the environment.

       .hlm [n]
              Set the maximum number of consecutive hyphenated lines to n.  If
              n  is negative, there is no maximum.  If omitted, n is -1.  This
              value is associated with the  environment.   Only  lines  output
              from  a  given  environment count towards the maximum associated
              with that environment.  Hyphens resulting from \%  are  counted;
              explicit hyphens are not.

       .hpf pattern‐file
              Read  hyphenation  patterns  from  pattern‐file.   This  file is
              sought in the same way that macro files are with the mso request
              or the -mname command‐line option to groff(1) and troff(1).

              The pattern‐file should have the same  format  as  (simple)  TeX
              pattern files.  The following scanning rules are implemented.

              • A  percent  sign  starts a comment (up to the end of the line)
                even if preceded by a backslash.

              • “Digraphs” like \$ are not supported.

              • “^^xx” (where each x is 0–9 or a–f) and ^^c  (character  c  in
                the code point range 0–127 decimal) are recognized; other uses
                of ^ cause an error.

              • No macro expansion is performed.

              • hpf  checks  for  the expression \patterns{...} (possibly with
                whitespace before or after the  braces).   Everything  between
                the  braces  is  taken as hyphenation patterns.  Consequently,
                “{” and “}” are not allowed in patterns.

              • Similarly, \hyphenation{...} gives a list of  hyphenation  ex‐
                ceptions.

              • \endinput is recognized also.

              • For  backwards  compatibility,  if  \patterns  is missing, the
                whole file is treated as a list of hyphenation  patterns  (but
                the  “%”  character is still recognized as the start of a com‐
                ment).

              Use the hpfcode request (see below) to map the encoding used  in
              hyphenation pattern files to groff’s input encoding.

              The  set  of hyphenation patterns is associated with the hyphen‐
              ation language set by the hla request.  The hpf request is  usu‐
              ally  invoked by a localization file loaded by the troffrc file.
              By default, troffrc loads the  localization  file  for  English.
              (As  of  groff 1.23.0, localization files for Czech (cs), German
              (de), English (en), French (fr), Japanese  (ja),  Swedish  (sv),
              and  Chinese  (zh) exist.)  For Western languages, the localiza‐
              tion file sets the hyphenation mode and loads  hyphenation  pat‐
              terns and exceptions.

              A  second  call  to hpf (for the same language) replaces the old
              patterns with the new ones.

              Invoking hpf causes an error if there  is  no  hyphenation  lan‐
              guage.

              If  no  hpf  request  is specified (either in the document, in a
              file loaded at startup, or in a macro package), GNU troff  won’t
              automatically hyphenate at all.

       .hpfa pattern‐file
              As hpf, except that the hyphenation patterns and exceptions from
              pattern‐file are appended to the patterns already applied to the
              hyphenation language of the environment.

       .hpfcode a b [c d] ...
              Define  mapping  values  for  character  codes in pattern files.
              This is an older mechanism no longer used by groff’s  own  macro
              files;  for  its  successor, see hcode above.  hpf or hpfa apply
              the mapping after reading or appending to  the  active  list  of
              patterns.   Its  arguments are pairs of character codes—integers
              from 0 to 255.  The request maps character code  a  to  code  b,
              code  c to code d, and so on.  Character codes that would other‐
              wise be invalid in groff can be used.  By  default,  every  code
              maps to itself except those for letters “A” to “Z”, which map to
              those for “a” to “z”.

       .hym [length]
              Set the (right) hyphenation margin to length.  If the adjustment
              mode  is  not  “b”  or  “n”, the line is not hyphenated if it is
              shorter than length.  Without an argument, the  default  hyphen‐
              ation  margin  is  reset  to  its default value, 0.  The default
              scaling unit is “m”.  The hyphenation margin is associated  with
              the  environment.   A  negative  argument resets the hyphenation
              margin to zero, emitting a warning in category “range”.

       .hys [hyphenation‐space]
              Suppress hyphenation of the line in adjustment modes “b” or “n”,
              if it can be justified by adding no more than  hyphenation‐space
              extra  space to each inter‐word space.  Without an argument, the
              hyphenation space adjustment threshold is  set  to  its  default
              value,  0.   The  default  scaling unit is “m”.  The hyphenation
              space adjustment threshold is associated with the current  envi‐
              ronment.   A  negative argument resets the hyphenation space ad‐
              justment threshold to  zero,  emitting  a  warning  in  category
              “range”.

       .itc n name
              As  “it”,  but lines interrupted with the \c escape sequence are
              not applied to the line count.

       .kern n
              If n is non‐zero or missing, enable pairwise  kerning  (the  de‐
              fault), otherwise disable it.

       .length reg anything
              Compute  the  number  of  characters  in anything and return the
              count in the register reg.  If reg doesn’t exist, it is created.
              anything is read in copy mode.

                     .ds xxx abcd\h'3i'efgh
                     .length yyy \*[xxx]
                     \n[yyy]
                     14

       .linetabs n
              If n is non‐zero or missing, enable  line‐tabs  mode,  otherwise
              disable  it (the default).  In this mode, tab stops are computed
              relative to the start of the pending output line, instead of the
              drawing position corresponding to the start of the  input  line.
              Line‐tabs mode is a property of the environment.

              For example, the following

                     .ds x a\t\c
                     .ds y b\t\c
                     .ds z c
                     .ta 1i 3i
                     \*x
                     \*y
                     \*z
              yields
                     a         b         c
              whereas in line‐tabs mode, the same input gives
                     a         b                   c
              instead.

       .lsm [name]
              Set  the leading space macro (trap) to name.  If there are lead‐
              ing space characters on an input line, name is invoked  in  lieu
              of the usual roff behavior; the leading spaces are removed.  The
              count  of  leading spaces on an input line is stored in \n[lsn],
              and the amount of corresponding horizontal  motion  in  \n[lss],
              irrespective  of  whether  a leading space trap is set.  When it
              is, the leading spaces are removed from the input line,  and  no
              motion  is produced before calling name.  If no argument is sup‐
              plied, the default leading space behavior is (re‐)established.

       .mso file
              As “so”, except that file is sought in the same  directories  as
              arguments  to  the  groff(1) and troff(1) -m command‐line option
              are (the “tmac path”).  If the file name to be interpolated  has
              the  form  name.tmac  and  it  isn’t found, mso tries to include
              tmac.name instead and vice versa.  If file  does  not  exist,  a
              warning  in  category  “file”  is emitted and the request has no
              other effect.

       .msoquiet file
              As mso, but no warning is emitted if file does not exist.

       .nop anything
              Interpret anything as if it were an input line.   nop  resembles
              “.if  1”;  it  puts  a break on the output if anything is empty.
              Unlike “if”, it cannot govern conditional blocks.  Its  applica‐
              tion  is to maintain consistent indentation within macro defini‐
              tions even when producing text lines.

       .nroff Make the n conditional expression evaluate  true  and  t  false.
              See troff.

       .open stream file
              Open  file  for writing and associate stream with it.  See write
              and close.

       .opena stream file
              As open, but if file exists, append to it instead of  truncating
              it.

       .output contents
              Emit  contents,  which  are  read in copy mode, to the formatter
              output; this is similar to \! used in the  top‐level  diversion.
              An initial neutral double quote in contents is stripped to allow
              the embedding of leading spaces.

       .pev   Report  the state of the current environment followed by that of
              all other environments to the standard error stream.

       .pnr   Write the names and values of all currently defined registers to
              the standard error stream.

       .psbb file
              Get the bounding box of a PostScript image file.  This file must
              conform to Adobe’s Document Structuring Conventions; the request
              attempts to extract the bounding box values from a %%BoundingBox
              comment.  After invocation, the x and y  coordinates  (in  Post‐
              Script  units)  of the lower left and upper right corners can be
              found in the registers \n[llx], \n[lly], \n[urx],  and  \n[ury],
              respectively.   If an error occurs, these four registers are set
              to zero.

       .pso command
              As “so”, except that input comes from the standard output stream
              of command.

       .ptr   Report the names and vertical positions  of  all  page  location
              traps to the standard error stream.  Empty slots in the list are
              shown  as well, because they can affect the visibility of subse‐
              quently planted traps.

       .pvs ±n
              Set the post‐vertical line spacing to n;  default  scaling  unit
              is  “p”.   With no argument, the post‐vertical line space is set
              to its previous value.

              In GNU troff, the distance between text  baselines  consists  of
              the  extra pre‐vertical line spacing set by the most negative \x
              argument on the pending output line, the vertical spacing  (vs),
              the extra post‐vertical line spacing set by the most positive \x
              argument  on the pending output line, and the post‐vertical line
              spacing set by this request.

       .rchar c ...
              Remove definition of each ordinary or special character c, undo‐
              ing the effect of a char,  fchar,  or  schar  request.   Glyphs,
              which  are defined by font description files, cannot be removed.
              Spaces and tabs may separate c arguments.

       .return
              Within a macro, return immediately.  If called with an argument,
              return twice, namely from the current macro and from  the  macro
              one level higher.  No effect otherwise.

       .rfschar f c ...
              Remove each fallback special character c for font f.  Spaces and
              tabs may separate c arguments.  See fschar.

       .rj [n]
              Right‐align the next n input lines.  Without an argument, right‐
              align  the  next input line.  rj implies “.ce 0”, and ce implies
              “.rj 0”.

       .rnn r1 r2
              Rename register r1 to r2.  If r1 doesn’t exist, the  request  is
              ignored.

       .schar c contents
              Define  global  fallback character c as contents.  See char; the
              distinction is that a character defined with  schar  is  located
              after  the  list  of fonts declared with the special request but
              before any mounted special fonts.

       .shc [c]
              Set the soft hyphen character, inserted when a word  is  hyphen‐
              ated automatically or at a hyphenation character, to c.  If c is
              omitted, the soft hyphen character is set to the default, \[hy].
              If the selected glyph does not exist in the font in use at a po‐
              tential  hyphenation  point, then the line is not broken at that
              point.  Neither character definitions  (char  and  similar)  nor
              translations  (tr and similar) are considered when assigning the
              soft hyphen character.

       .shift n
              In a macro, shift the arguments by n positions: argument  i  be‐
              comes  argument  i-n;  arguments 1 to n are no longer available.
              If n is missing, arguments are shifted by 1.  No  effect  other‐
              wise.

       .sizes s1 s2 ... sn [0]
              Set  the  available  type sizes to s1, s2, ... sn scaled points.
              The list of sizes can be terminated by an optional “0”.  Each si
              can also be a range m–n.  In contrast to the device  description
              file  directive  of the same name (see groff_font(5)), the argu‐
              ment list can’t extend over more than one line.

       .soquiet file
              As “so”, but no warning is emitted if file does not exist.

       .special f ...
              Declare each font f as special,  searching  it  for  glyphs  not
              found  in  the  selected  font.  Without arguments, this list of
              special fonts is made empty.

       .spreadwarn [limit]
              Emit a break warning if the additional space inserted  for  each
              space  between  words in an output line adjusted to both margins
              with “.ad b” is larger than or equal to limit.  A negative value
              is treated as zero; an absent argument toggles  the  warning  on
              and  off without changing limit.  The default scaling unit is m.
              At startup, spreadwarn is inactive and limit is 3 m.

              For example, “.spreadwarn 0.2m” causes a warning if break  warn‐
              ings  are  not  suppressed  and troff must add 0.2 m or more for
              each inter‐word space in a line.

       .stringdown str
       .stringup str
              Alter the string named str by replacing each of its  bytes  with
              its  lowercase (down) or uppercase (up) version (if one exists).
              Special characters (see groff_char(7)) will often  transform  in
              the  expected  way  due to the regular naming convention for ac‐
              cented characters.  When they  do  not,  use  substrings  and/or
              catenation.

                     .ds resume R\['e]sum\['e]\"
                     \*[resume]
                     .stringdown resume
                     \*[resume]
                     .stringup resume
                     \*[resume]
                     Résumé résumé RÉSUMÉ

       .sty n s
              Associate abstract style s with font mounting position n.

       .substring string start [end]
              Replace  the  string  named string with its substring bounded by
              the indices start and end, inclusively.  The first character  in
              the string has index 0.  If end is omitted, it is implicitly set
              to the largest valid value (the string length minus one).  Nega‐
              tive  indices  count  backwards  from the end of the string: the
              last character has index -1, the character before the  last  has
              index -2, and so on.

                     .ds xxx abcdefgh
                     .substring xxx 1 -4
                     \*[xxx]
                     bcde
                     .substring xxx 2
                     \*[xxx]
                     de

       .tkf f s1 n1 s2 n2
              Enable track kerning for font f.  When the current font is f the
              width  of  every  glyph is increased by an amount between n1 and
              n2; when the current type size is less than or equal to  s1  the
              width is increased by n1; when it is greater than or equal to s2
              the width is increased by n2; when the type size is greater than
              or  equal  to  s1  and  less than or equal to s2 the increase in
              width is a linear function of the type size.

       .tm1 message
              As tm request, but strips a leading neutral  double  quote  from
              message to allow the embedding of leading spaces.

       .tmc message
              As tm1 request, but does not append a newline.

       .trf file
              Transparently  output  the  contents of file file.  Each line is
              output as if preceded by \!; however, the lines are not  subject
              to  copy‐mode  interpretation.   If the file does not end with a
              newline, then a newline is added.  Unlike cf, file  cannot  con‐
              tain characters that are invalid as input to GNU troff.

              For example, you can define a macro x containing the contents of
              file f, using

                     .di x
                     .trf f
                     .di

       .trin abcd
              This  is  the same as the tr request except that the asciify re‐
              quest uses the character code  (if  any)  before  the  character
              translation.  Example:

                     .trin ax
                     .di xxx
                     a
                     .br
                     .di
                     .xxx
                     .trin aa
                     .asciify xxx
                     .xxx

              The result is “x a”.  Using tr, the result would be “x x”.

       .trnt abcd
              This  is the same as the tr request except that the translations
              do not apply to text that is transparently throughput into a di‐
              version with \!.  For example,

                     .tr ab
                     .di x
                     \!.tm a
                     .di
                     .x

              prints b; if trnt is used instead of tr it prints a.

       .troff Make the t conditional expression evaluate  true  and  n  false.
              See nroff.

       .unformat div
              Unformat  the  diversion  div.  Unlike asciify, unformat handles
              only tabs and spaces between words, the latter  usually  arising
              from spaces or newlines in the input.  Tabs are treated as input
              tokens,  and spaces become adjustable again.  The vertical sizes
              of lines are not preserved, but glyph  information  (font,  type
              size, space width, and so on) is retained.

       .vpt n If n is non‐zero or missing, enable vertical position traps (the
              default),  otherwise  disable them.  Vertical position traps are
              those set by the ch, wh, and dt requests.

       .warn [n]
              Select the categories, or “types”, of reported warnings.   n  is
              the  sum of the numeric codes associated with each warning cate‐
              gory that is to be enabled; all other categories  are  disabled.
              The  categories and their associated codes are listed in section
              “Warnings” of troff(1).  For example,  “.warn  0”  disables  all
              warnings, and “.warn 1” disables all warnings except those about
              missing glyphs.  If no argument is given, all warning categories
              are enabled.

       .warnscale si
              Set  the  scaling unit used in warnings to si.  Valid values for
              si are u, i (the default), c, p, and P.

       .while cond‐expr anything
              Evaluate the conditional expression  cond‐expr,  and  repeatedly
              execute  anything  unless  and  until cond‐expr evaluates false.
              anything, which is often a conditional block, is referred to  as
              the while request’s body.

              troff  treats the body of a while request similarly to that of a
              de request (albeit one not read in copy mode), but stores it un‐
              der an internal name and deletes it when the loop finishes.  The
              operation of a macro containing a while request can slow signif‐
              icantly if the while body is large.  Each time the macro is exe‐
              cuted, the while body is parsed and stored again.  An often bet‐
              ter solution—and one that is more  portable,  since  AT&T  troff
              lacked  the while request—is to instead write a recursive macro.
              It will be parsed only once (unless you redefine it).   To  pre‐
              vent  infinite  loops, the default number of available recursion
              levels is 1,000 or somewhat  less  (because  things  other  than
              macro  calls  can  be on the input stack).  You can disable this
              protective measure, or raise the limit, by  setting  the  slimit
              register.  See section “Debugging” below.

              If  a  while  body  begins with a conditional block, its closing
              brace must end an input line.

              The break and continue requests alter a  while  loop’s  flow  of
              control.

       .write stream anything
              Write  anything  to  stream, which must previously have been the
              subject of an open request, followed by a newline.  anything  is
              read  in copy mode.  An initial neutral double quote in anything
              is stripped to allow the embedding of leading spaces.

       .writec stream anything
              As write, but without a trailing newline.

       .writem stream name
              Write the contents of the macro or string name to stream,  which
              must  previously have been the subject of an open request.  name
              is read in copy mode.

   Extended requests
       .cf file
              In a diversion, embed an object which, when reread,  will  cause
              the  contents  of  file to be copied verbatim to the output.  In
              AT&T troff, the contents of file are immediately copied  to  the
              output  regardless  of  whether a diversion is being written to;
              this behavior is so anomalous that it must be considered a bug.

       .de name [end‐name]
       .am name [end‐name]
       .ds name [contents]
       .as name [contents]
              In compatibility mode, these requests behave similarly  to  de1,
              am1, ds1, and as1, respectively: a “compatibility save” token is
              inserted  at  the beginning, and a “compatibility restore” token
              at the end, with compatibility mode switched  on  during  execu‐
              tion.

       .hy n  New  values  16 and 32 are available; the former enables hyphen‐
              ation before the last character in a word, and  the  latter  en‐
              ables hyphenation after the first character in a word.

       .ss word‐space‐size [additional‐sentence‐space‐size]
              A second argument sets the amount of additional space separating
              sentences  on  the same output line.  If omitted, this amount is
              set to word‐space‐size.  Both arguments are in twelfths of  cur‐
              rent  font’s  space  width (typically one‐fourth to one‐third em
              for Western scripts; see groff_font(5)).  The default  for  both
              parameters is 12.  Negative values are erroneous.

       .ta [[n1 n2 ... nn ]T r1 r2 ... rn]
              groff supports an extended syntax to specify repeating tab stops
              after  the  “T” mark.  These values are always taken as relative
              distances from the previous tab stop.  This is the idiomatic way
              to specify tab stops at equal intervals in groff.

              The syntax summary above instructs groff to set  tabs  at  posi‐
              tions n1, n2, ..., nn, then at nn+r1, nn+r2, ..., nn+rn, then at
              nn+rn+r1, nn+rn+r2, ..., nn+rn+rn, and so on.

   New registers
       GNU  troff  exposes  more formatter state via many new read‐only regis‐
       ters.  Their names often correspond to the requests that affect them.

       \n[.br]     Within a macro call, interpolate 1 if the macro  is  called
                   with the “normal” control character (“.” by default), and 0
                   otherwise.   This facility allows the reliable modification
                   of requests.  Using this register outside of a macro defin‐
                   ition makes no sense.

                          .als bp*orig bp
                          .de bp
                          .tm before bp
                          .ie \\n[.br] .bp*orig
                          .el 'bp*orig
                          .tm after bp
                          ..

       \n[.C]      Interpolate 1 if compatibility mode is in effect, 0  other‐
                   wise.  See cp.

       \n[.cdp]    Interpolate  depth  of last glyph added to the environment.
                   It is positive if the glyph extends below the baseline.

       \n[.ce]     Interpolate number of input lines remaining to be centered.

       \n[.cht]    Interpolate height of last glyph added to the  environment.
                   It is positive if the glyph extends above the baseline.

       \n[.color]  Interpolate 1 if colors are enabled, 0 otherwise.

       \n[.cp]     Within  a “do” request, interpolate the saved value of com‐
                   patibility mode (see \n[.C] above).

       \n[.csk]    Interpolate skew of last glyph added  to  the  environment.
                   The  skew  of a glyph is how far to the right of the center
                   of a glyph the center of an accent over that  glyph  should
                   be placed.

       \n[.ev]     Interpolate name of current environment.  This is a string‐
                   valued register.

       \n[.fam]    Interpolate name of default font family.  This is a string‐
                   valued register.

       \n[.fn]     Interpolate  resolved name of the selected font.  This is a
                   string‐valued register.

       \n[.fp]     Interpolate next free font mounting position.

       \n[.g]      Interpolate 1.  Test with “if” or ie to check  whether  GNU
                   troff is the formatter.

       \n[.height] Interpolate font height.  See \H.

       \n[.hla]    Interpolate  hyphenation language of the environment.  This
                   is a string‐valued register.

       \n[.hlc]    Interpolate count of immediately preceding consecutive  hy‐
                   phenated lines in the environment.

       \n[.hlm]    Interpolate  maximum number of consecutive hyphenated lines
                   allowed in the environment.

       \n[.hy]     Interpolate hyphenation mode of the environment.

       \n[.hym]    Inteprolate hyphenation margin of the environment.

       \n[.hys]    Interpolate hyphenation space adjustment threshold  of  the
                   environment.

       \n[.in]     Interpolate  indentation  amount  applicable to the pending
                   output line.

       \n[.int]    Interpolate 1 if the previous output line  was  interrupted
                   (ended with \c), 0 otherwise.

       \n[.kern]   Interpolate 1 if pairwise kerning is enabled, 0 otherwise.

       \n[.lg]     Interpolate ligature mode.

       \n[.linetabs]
                   Interpolate 1 if line‐tabs mode is enabled, 0 otherwise.

       \n[.ll]     Interpolate  line  length  applicable to the pending output
                   line.

       \n[.lt]     Interpolate title line length.

       \n[.m]      Interpolate name of the selected stroke color.  This  is  a
                   string‐valued register.

       \n[.M]      Interpolate  name  of  the  selected fill color.  This is a
                   string‐valued register.

       \n[.ne]     Interpolate amount of space demanded by the most recent  ne
                   request that caused a page location trap to be sprung.  See
                   \n[.trunc].

       \n[.nm]     Interpolate  1 if output line numbering is enabled (even if
                   temporarily suppressed), 0 otherwise.

       \n[.ns]     Interpolate 1 if no‐space mode is enabled, 0 otherwise.

       \n[.O]      Interpolate output suppression level.  See \O.

       \n[.P]      Interpolate 1 if the current page is selected  for  output.
                   See -o command‐line option to troff(1).

       \n[.pe]     Interpolate 1 during page ejection, 0 otherwise.

       \n[.pn]     Interpolate  next  page  number  (either that set by pn, or
                   that of the current page plus 1).

       \n[.ps]     Interpolate type size in scaled points.

       \n[.psr]    Interpolate most recently requested  type  size  in  scaled
                   points.

       \n[.pvs]    Interpolate post‐vertical line spacing amount.

       \n[.rj]     Interpolate  number  of  input lines remaining to be right‐
                   aligned.

       \n[.slant]  Interpolate font slant.  See \S.

       \n[.sr]     Interpolate most recently requested type size in points  as
                   a decimal fraction.  This is a string‐valued register.

       \n[.ss]
       \n[.sss]    Interpolate  values  of  minimal inter‐word space and addi‐
                   tional inter‐sentence space, respectively, in  twelfths  of
                   the space width of the selected font.

       \n[.sty]    Interpolate  selected abstract font style, if any.  This is
                   a string‐valued register.

       \n[.tabs]   Interpolate representation of the tab stop  settings  in  a
                   form suitable for passage to the ta request.

       \n[.trunc]  Interpolate  amount of vertical space truncated by the most
                   recently sprung page location trap, or,  if  the  trap  was
                   sprung  by  an ne request, minus the amount of vertical mo‐
                   tion produced by the ne request.  In other  words,  at  the
                   point  a  trap is sprung, \n[.trunc] represents the differ‐
                   ence of what the vertical position would have been but  for
                   the  trap, and what the vertical position actually is.  See
                   \n[.ne].

       \n[.U]      Interpolate 1 if in unsafe mode, 0 otherwise.  See -U  com‐
                   mand‐line option to troff(1).

       \n[.vpt]    Interpolate  1  if  vertical  position  traps  are enabled,
                   0 otherwise.

       \n[.warn]   Interpolate  warning  mode.   See  section  “Warnings”   of
                   troff(1).

       \n[.x]      Interpolate  major version number of the running troff for‐
                   matter.  For example, if the version number is 1.23.0, then
                   \n[.x] contains 1.

       \n[.y]      Interpolate minor version number of the running troff  for‐
                   matter.  For example, if the version number is 1.23.0, then
                   \n[.y] contains 23.

       \n[.Y]      Interpolate revision number of the running troff formatter.
                   For  example,  if the version number is 1.23.0, then \n[.Y]
                   contains 0.

       \n[.zoom]   Interpolate magnification of font, in thousandths, or 0  if
                   magnification unused.  See fzoom.

       The following (writable) registers are set by the psbb request.

       \n[llx]
       \n[lly]
       \n[urx]
       \n[ury]
              Interpolate  the (upper, lower, left, right) bounding box values
              (in PostScript units) of the most recently processed  PostScript
              image.

       The following (writable) registers are set by the \w escape sequence.

       \n[rst]
       \n[rsb] Like  \n[st]  and \n[sb], but taking account of the heights and
               depths of glyphs.  In other words, these  registers  store  the
               highest  and lowest vertical positions attained by the argument
               formatted by the \w escape sequence, doing what AT&T troff doc‐
               umented \n[st] and \n[sb] as doing.

       \n[ssc] The amount of horizontal space (possibly negative) that  should
               be added to the last glyph before a subscript.

       \n[skw] How  far to right of the center of the last glyph in the \w ar‐
               gument, the center of an accent from a  roman  font  should  be
               placed over that glyph.

       Other  writable  registers  are as follows.  Those relating to date and
       time are initialized using localtime(3) at formatter startup.

       \n[c.]      Interpolate input line number.  \n[.c] is a read‐only alias
                   of this register.

       \n[hours]   Interpolate number of hours elapsed since midnight.

       \n[hp]      Interpolate horizontal position relative  to  that  at  the
                   start of the input line.

       \n[lsn]
       \n[lss]     Interpolate  count  of  leading  spaces  on  input line and
                   amount of corresponding horizontal motion, respectively.

       \n[minutes] Interpolate number of minutes elapsed in the hour.

       \n[seconds] Interpolate number of seconds elapsed in the minute.

       \n[systat]  Interpolate return value of system(3) function executed  by
                   most recent sy request.

       \n[slimit]  Interpolates  maximum quantity of objects on troff’s inter‐
                   nal input stack (default: 1000).  If non‐positive, there is
                   no limit: recursion can continue until  program  memory  is
                   exhausted.

       \n[year]    Interpolate  Gregorian  year.   AT&T troff’s \[yr] interpo‐
                   lates the Gregorian year minus 1900.

   Miscellaneous
       GNU troff predefines one string, .T, containing the argument  given  to
       the  -T command‐line option, namely the output device (for example, pdf
       or utf8).  The (read‐only) register .T interpolates 1 if GNU  troff  is
       run with the -T command‐line option, and 0 otherwise.

       A font not listed in the output device’s DESC file’s fonts directive is
       automatically  mounted  at  the next available font position when it is
       selected.  If you mount a font explicitly  with  the  fp  request,  you
       should  do  so  on the first unused position, which can be found in the
       .fp register.

       Unparameterized string interpolation does not conceal the arguments  to
       a  macro  being  interpreted.  Thus, in a macro definition, the call of
       another macro with the existing argument list,
              .xx \\$@
       is more efficiently done with
              \\*[xx]\\
       (that is, with string interpolation).  The trailing backslashes prevent
       the final newline in the macro definition from being interpolated,  po‐
       tentially  putting  an  unwanted blank line on the output.  See section
       “Punning Names” in groff(7).

       If a font  description  file  contains  pairwise  kerning  information,
       glyphs  from  that  font are kerned.  Kerning between two glyphs can be
       inhibited by placing a dummy character \& between them.

       GNU troff keeps track of the nesting depth of escape sequence  interpo‐
       lations and other uses of delimiters, as in the tl request and the out‐
       put comparison operator (that is, input like 'foo'bar' as a conditional
       expression),  so  the only characters you need to avoid using as delim‐
       iters are those that appear in the arguments you input,  not  any  that
       result from interpolation.  Typically, ' works fine.  Use visible char‐
       acters  as delimiters in GNU troff, not “ASCII” controls like BEL (Con‐
       trol+G).  The implementation of \$@ ensures that the double quotes sur‐
       rounding an argument appear at an interpolation  depth  different  from
       that  of  the  arguments themselves.  Similarly, in bracket‐form escape
       sequences like \f[ZCMI], a right bracket ] does not  end  the  sequence
       unless  it  occurs at the same interpolation depth as the opening [, so
       input like
              \f[\*[my‐family]\*[my‐style]]
       works as desired.  In compatibility mode, no attention is paid  to  the
       interpolation depth.

       In  GNU  troff,  the  tr  request can map characters to the unbreakable
       space escape sequence \~ as a special case (tr normally  operates  only
       on  characters).  This feature replaces the odd‐parity tr mapping trick
       used in AT&T troff documents, where a character, often ~,  was  “sacri‐
       ficed”  by  mapping  it  to “nothing”, drafting it into use as an unad‐
       justable, unbreakable space.  (This  feature  was  gratuitous  even  in
       early  AT&T troff, which supported the \space escape sequence by 1976.)
       Often, it makes more sense to use GNU troff’s \~  escape  sequence  in‐
       stead,  which  has been adopted by every other active troff implementa‐
       tion except that of Illumos,  as  well  as  by  the  non‐troff  mandoc.
       Translation of a character to \~ is unnecessary.

       GNU troff permits tabs and spaces after the first dot on a control line
       that ends a macro definition.
              .if t \{\
              .  de bar
              .    nop Hello, I'm 'bar'.
              .  .
              .\}

Formatter output
       The page description language output by GNU troff is modeled after that
       used  by  AT&T  troff  once the latter adopted a device‐independent ap‐
       proach in the early 1980s.  Only the differences are  documented  here.
       For a fuller discussion, see groff_out(5).

       Glyph  and font names can be of arbitrary length; postprocessors should
       not assume that they are at most two characters.  A glyph to be format‐
       ted is always drawn from the current font; in contrast to AT&T  device‐
       independent  troff,  drivers  need  not  search special fonts to find a
       glyph.

   Units
       The argument to the s command is in scaled points (units  of  points/n,
       where  n  is  the  argument to the sizescale command in the DESC file).
       The argument to the “x H” command is also in scaled points.

   Simple commands
       If the tcommand directive is present in the output device’s DESC  file,
       GNU troff employs the following two commands.

       t xyz...
              Typeset  word  xyz;  that  is, set a sequence of ordinary glyphs
              named x, y, z, ..., terminated by a space  or  newline;  an  op‐
              tional  second integer argument is ignored (this allows the for‐
              matter to generate an even number of arguments).  Each glyph  is
              set  at  the  current drawing position, and the position is then
              advanced horizontally by the glyph’s width.  A glyph’s width  is
              read  from  its  metrics in the font description file, scaled to
              the current type size, and rounded to a multiple of the horizon‐
              tal motion quantum.  Use the C command to emplace glyphs of spe‐
              cial characters.

       u n xyz...
              Typeset word xyz with track kerning.  As t,  but  after  placing
              each  glyph,  the  drawing position is further advanced horizon‐
              tally by n basic units.

       New commands implement color support.

       mc cyan magenta yellow
       md
       mg gray
       mk cyan magenta yellow black
       mr red green blue
              Set the components of the stroke color with respect  to  various
              color  spaces.  md resets the stroke color to the default value.
              The arguments are integers in the range 0 to 65535.

       A new device control subcommand is available.

       x u n  If n is 1, start underlining of spaces.  If n is 0, stop  under‐
              lining of spaces.  This facility is needed for the cu request in
              nroff mode and is ignored otherwise.

   Extended drawing commands
       GNU  pic does not produce troff escape sequences employing these exten‐
       sions if its -n option is given.

       Df n   Set the shade of gray used to fill geometric objects to n, which
              must be an integer.  0 corresponds to white and 1000  to  black.
              A grayscale ramp spans the two.  A value outside this range uses
              the  stroke  color as the fill color.  The fill color is opaque.
              Normally the default is black, but some drivers  may  provide  a
              way  of changing this.  Df is obsolete since 2002, superseded by
              DFg below.

              The corresponding \D'f' escape sequence should not be used:  its
              argument is rounded to an integer multiple of the horizontal mo‐
              tion quantum, which can limit the precision of n.

       DC d   Draw  a  filled  circle of diameter d with its leftmost point at
              the drawing position.

       DE h v Draw a filled ellipse, of horizontal axis h and vertical axis v,
              with its leftmost point at the drawing position.

       Dp dx1dy1...dxndyn
              Draw a polygon with, for i=1,...,n+1,  its  ith  vertex  at  the
              drawing  position +ij−=Σ11(dxj,dyj).  groff output drivers automati‐
              cally close polygons, drawing a  line  from  (dxn,dyn)  back  to
              (dx1,dy1).   The  drawing position is left at the last specified
              vertex, but this may change in a future version  of  GNU  troff.
              Heirloom  Doctools  troff,  like  DWB troff, by default does not
              close the polygon.  In its groff  compatibility  mode,  Heirloom
              closes  the  polygon  but leaves the drawing position unchanged—
              that is, at the polygon’s initial drawing position.

              At the moment, GNU pic uses this command only to generate trian‐
              gles and rectangles.

       DP dx1dy1...dxndyn
              As Dp, but draw a filled rather than a stroked polygon.

       Dt n   Set the line thickness to n basic units.  AT&T troff output dri‐
              vers use a thickness proportional to the type size; this is  the
              GNU troff default.  A negative n requests this explicitly.  An n
              of zero selects the smallest available line thickness.

       A difficulty arises in how the drawing position should be changed after
       the  execution  of  these commands.  This has little importance to most
       users, since the output of GNU grn and  pic  does  not  depend  on  it.
       Given a drawing command of the form Dz x1y1...xnyn, where z is not c or
       e,  AT&T troff treats each xi as a horizontal motion, each yi as a ver‐
       tical one, and therefore assumes that the width of the drawn object  is
       in=Σ1xi, and its height is in=Σ1yi.  (Verify its assumption about height by
       examining the st and sb registers after using such a drawing command in
       a  \w  escape sequence).  For the sake of compatibility, GNU troff also
       follows this rule, even though it frustrates extensions to the  D  com‐
       mand that set drawing parameters rather than rendering objects, produc‐
       ing  ugly  results in the case of Dt and Df, or otherwise don’t parame‐
       terize objects as a series of vertices, as with GNU troff’s filled  el‐
       lipse,   DE.   Thus  after  executing  a  D  command  of  the  form  Dz
       x1y1...xnyn, the drawing position should be increased by (in=Σ1xi,in=Σ1yi).
       In a future release, GNU troff and its output drivers may  abandon  the
       application of this assumption to drawing commands not explicitly spec‐
       ified in the AT&T “Troff User’s Manual”.

       Fill color selection is implemented with another set of extensions.

       DFc cyan magenta yellow
       DFd
       DFg gray
       DFk cyan magenta yellow black
       DFr red green blue
              Set  the  components of the fill color as described under the \M
              escape sequence above.  DFd restores the device’s  default  fill
              color.  The drawing position is not updated, in contrast to Df.

   Device control syntax extension
       GNU troff introduces a line continuation convention, permitting the ar‐
       gument  to the x X command to contain newlines.  A newline in the input
       is transformed to the sequence “newline+”.  When interpreting  an  x  X
       command,  a  postprocessor should therefore be prepared for a plus sign
       after a newline; if it occurs, preserve the newline, discard  the  plus
       sign,  and  continue  to collect the input into the argument of the x X
       command.  A newline not followed by a plus sign terminates the x X com‐
       mand.  An application of this feature is the embedding of PostScript or
       PDF language command streams into troff output.

       GNU troff guarantees that the first three output commands it emits  are
       as follows.

              x T device
              x res n h v
              x init

Debugging
       In  addition  to  AT&T troff’s debugging features, GNU troff emits more
       error diagnostics when syntactical or semantic nonsense is  encountered
       and supports several warning categories; the output of these can be se‐
       lected  with  warn.   Also  see the -E, -w, and -W options of troff(1).
       Backtraces can be automatically produced when errors or warnings  occur
       (the -b option of troff(1)) or generated on demand (backtrace).

       groff also adds more flexible diagnostic output requests (tmc and tm1).
       More  aspects  of  formatter  state  can be examined with requests that
       write lists of defined registers (pnr), environments  (pev),  and  page
       location traps (ptr) to the standard error stream.

Implementation differences
       GNU  troff’s  features sometimes cause incompatibilities with documents
       written assuming old implementations of troff.  Some GNU extensions  to
       troff are supported by other implementations.

       When  adjusting  to  both  margins,  AT&T troff at first adjusts spaces
       starting from the right; GNU troff begins from the left.   Both  imple‐
       mentations adjust spaces from opposite ends on alternating output lines
       to prevent “rivers” in the text.

       GNU troff does not always hyphenate words as AT&T troff does.  The AT&T
       implementation uses a set of hard‐coded rules specific to U.S. English,
       while  GNU  troff  uses language‐specific hyphenation pattern files de‐
       rived from TeX.  In some versions of troff there was limited  space  to
       store  hyphenation  exceptions (arguments to the hw request); GNU troff
       has no such restriction.

       Long names may be GNU troff’s most obvious innovation.  AT&T troff  in‐
       terprets  “.dsabcd” as defining a string “ab” with contents “cd”.  Nor‐
       mally, GNU troff interprets this as a call of a macro  named  “dsabcd”.
       AT&T  troff also interprets \*[ and \n[ as an interpolation of a string
       or register, respectively, called “[”.  In GNU troff, however, the  “[”
       is  normally  interpreted  as beginning the enclosure of a long identi‐
       fier.  In compatibility mode, GNU troff interprets names in the  tradi‐
       tional way, which means that they are limited to one or two characters.
       See the -C option in troff(1) and, above, the .C and .cp registers, and
       cp and “do” requests, for more on compatibility mode.

       The  register \n[.cp] is specialized and may require a statement of ra‐
       tionale.  When writing macro packages or documents that use  GNU  troff
       features  and  which may be mixed with other packages or documents that
       do not—common scenarios include serial processing of man pages  or  use
       of the “so” or mso requests—you may desire correct operation regardless
       of  compatibility  mode  enablement in the surrounding context.  It may
       occur to you to save the existing value of \n(.C into a register,  say,
       _C,  at  the  beginning  of your file, turn compatibility mode off with
       “.cp  0”,  then  restore  it  from  that  register  at  the  end   with
       “.cp \n(_C”.  At the same time, a modular design of a document or macro
       package  may  lead you to multiple layers of inclusion.  You cannot use
       the same register name everywhere lest you “clobber” the value  from  a
       preceding  or enclosing context.  The two‐character register name space
       of AT&T troff is confining and mnemonically challenging; you  may  wish
       to use GNU troff’s more capacious name space.  However, attempting “.nr
       _my_saved_C  \n(.C”  will  not work in compatibility mode; the register
       name is too long.  “This is exactly what .do is for,” you  think,  “.do
       nr  _my_saved_C  \n(.C”.   The  foregoing will always save zero to your
       register, because “do” turns compatibility mode off while it interprets
       its argument list.  What you need is:
              .do nr _my_saved_C \n[.cp]
              .cp 0
       at the beginning of your file, followed by
              .cp \n[_my_saved_C]
              .do rr _my_saved_C
       at the end.  As in the C language, we all have to share  one  big  name
       space, so choose a register name that is unlikely to collide with other
       uses.

       The  existence  of  the  .T string is a common feature of post‐CSTR #54
       troffs—DWB 3.3, Solaris, Heirloom Doctools, and Plan 9 troff  all  sup‐
       port  it—but valid values are specific to each implementation.  The be‐
       havior of the .T register in GNU troff differs from AT&T  troff,  which
       interpolated 1 only if nroff was the formatter and was called with -T.

       The lf request sets the number of the current input line in AT&T troff,
       and the next in GNU troff.

       AT&T  troff  had  only  environments  named  “0”, “1”, and “2”.  In GNU
       troff, any number of environments may exist, using  any  valid  identi‐
       fiers for their names.

       GNU  troff  normally  tracks the interpolation depth of escape sequence
       parameters and other delimited structures,  but  not  in  compatibility
       mode.  See section “Miscellaneous” above.

       In compatibility mode, the escape sequences \f, \H, \m, \M, \R, \s, and
       \S are transparent at the beginning of an input line for the purpose of
       recognizing  a  control  character, because they modify formatter state
       (\R) or properties of the environment (the rest) and therefore  do  not
       create  output  nodes.   For example, this code produces bold output in
       both cases, but the text differs,
              .de xx '
              Hello!
              ..
              \fB.xx\fP
       formatting “.xx” normally and “Hello!” in compatibility mode.

       GNU troff request names unrecognized  by  other  troff  implementations
       will  likely be ignored; escape sequences that are GNU troff extensions
       are liable to format their function selector character.   For  example,
       the adjustable, non‐breaking space escape sequence \~ is also supported
       by  Heirloom  Doctools  troff  050915  (September  2005),  mandoc 1.9.5
       (2009‐09‐21), neatroff (commit 1c6ab0f6e, 2016‐09‐13), and Plan 9  from
       User  Space  troff  (commit  93f8143600,  2022‐08‐12),  but  not by So‐
       laris/Illumos troffs, which will render it as ~.

       GNU troff does not allow the use of the escape sequences  \|,  \^,  \&,
       \{,  \},  \space,  \',  \`,  \-, \_, \!, \%, or \c in identifiers; AT&T
       troff does.  The \A escape sequence (see subsection “Escape  sequences”
       above) may be helpful in avoiding their use.

       Normally, the syntax form \sn accepts only a single character (a digit)
       for  n,  consistently  with  other forms that originated in AT&T troff,
       like \*, \$, \f, \g, \k, \n, and \z.  In  compatibility  mode  only,  a
       non‐zero  n  must  be in the range 4–39.  Legacy documents relying upon
       this quirk of parsing should be migrated to another  \s  form.   [Back‐
       ground:  The Graphic Systems C/A/T phototypesetter (the original device
       target for AT&T troff) supported only a few discrete type sizes in  the
       range 6–36 points, so Ossanna contrived a special case in the parser to
       do what the user must have meant.  Kernighan warned of this in the 1992
       revision  of CSTR #54 (§2.3), and more recently, McIlroy referred to it
       as a “living fossil”.]

       Fractional type sizes cause one noteworthy  incompatibility.   In  AT&T
       troff  the ps request ignores scaling units and thus “.ps 10u” sets the
       type size to 10 points, whereas in GNU troff it sets the type  size  to
       10 scaled points, which may be a much smaller measurement.  See subsec‐
       tion “Fractional type sizes and new scaling units” above.

       The  ab request differs from AT&T troff: GNU troff writes no message to
       the standard error stream if no arguments are given, and it exits  with
       a failure status instead of a successful one.

       The  bp  request  differs  from AT&T troff: GNU troff does not accept a
       scaling unit on the argument, a page number; the former (somewhat  use‐
       lessly) does.

       In AT&T troff the pm request reports macro, string, and diversion sizes
       in  units  of  128‐byte blocks, and an argument reduces the report to a
       sum of the above in the same units.  GNU troff  ignores  any  arguments
       and reports the sizes in bytes.

       Unlike AT&T troff, GNU troff does not ignore the ss request if the out‐
       put is a terminal device; instead, the values of minimum inter‐word and
       additional  inter‐sentence  space  are each rounded down to the nearest
       multiple of 12.

       In GNU troff there is a fundamental  difference  between  (unformatted)
       characters and (formatted) glyphs.  Everything that affects how a glyph
       is  output  is  stored  with the glyph node; once a glyph node has been
       constructed, it is unaffected by any subsequent requests that are  exe‐
       cuted, including bd, cs, tkf, tr, or fp requests.  Normally, glyphs are
       constructed from characters immediately before the glyph is added to an
       output  line.   Macros,  diversions,  and strings are all, in fact, the
       same type of object; they contain a sequence  of  intermixed  character
       and  glyph  nodes.  Special characters transform from one to the other:
       before being added to the output, they behave as characters; afterward,
       they are glyphs.  A glyph node does not behave like  a  character  node
       when it is processed by a macro: it does not inherit any of the special
       properties  that the character from which it was constructed might have
       had.  For example, the input
              .di x
              \\\\
              .br
              .di
              .x
       produces “\\” in GNU troff.  Each pair of backslashes becomes one back‐
       slash glyph; the resulting backslashes are thus not interpreted as  es‐
       cape  characters when they are reread as the diversion is output.  AT&T
       troff would interpret them as escape characters when rereading them and
       end up printing one “\”.

       One way to format a backslash in most documents is with the  \e  escape
       sequence;  this  formats the glyph of the current escape character, re‐
       gardless of whether it is used in a diversion; it also  works  in  both
       GNU  troff  and  AT&T  troff.  (Naturally, if you’ve changed the escape
       character, you need to prefix the “e” with whatever  it  is—and  you’ll
       likely get something other than a backslash in the output.)

       The other correct way, appropriate in contexts independent of the back‐
       slash’s  common use as a roff escape character—perhaps in discussion of
       character sets or other programming languages—is the  character  escape
       \(rs  or  \[rs],  for  “reverse  solidus”,  from its name in the ECMA‐6
       (ISO/IEC 646) standard.  [This escape sequence is not portable to  AT&T
       troff,  but is to its lineal descendant, Heirloom Doctools troff, as of
       its 060716 release (July 2006).]

       To store an escape sequence in a diversion that is interpreted when the
       diversion is reread, either use the traditional \!  transparent  output
       facility,  or,  if this is unsuitable, the new \? escape sequence.  See
       subsection “Escape  sequences”  above  and  sections  “Diversions”  and
       “gtroff Internals” in Groff: The GNU Implementation of troff, the groff
       Texinfo manual.

       In the somewhat pathological case where a diversion exists containing a
       partially  collected  line  and  a partially collected line at the top‐
       level diversion has never existed, AT&T troff will output the partially
       collected line at the end of input; GNU troff will not.

   Formatter output incompatibilities
       Its extensions notwithstanding, the groff  intermediate  output  format
       has some incompatibilities with that of AT&T troff, but better compati‐
       bility is sought; problem reports and patches are welcome.  The follow‐
       ing incompatibilities are known.

       • The  drawing  position  after rendering polygons is inconsistent with
         AT&T troff practice.  Other implementations  have  diverged  on  this
         point as well.

       • The output cannot be easily rescaled to other devices as AT&T troff’s
         could.

Authors
       This  document was written by James Clark ⟨jjc@jclark.com⟩, Werner Lem‐
       berg ⟨wl@gnu.org⟩, Bernd Warken ⟨groff-bernd.warken-72@web.de⟩, and  G.
       Branden Robinson ⟨g.branden.robinson@gmail.com⟩.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       “Troff  User’s  Manual” by Joseph F. Ossanna, 1976 (revised by Brian W.
       Kernighan, 1992), AT&T Bell Laboratories  Computing  Science  Technical
       Report No. 54, widely called simply “CSTR #54”, documents the language,
       device and font description file formats, and output format referred to
       collectively in groff documentation as AT&T troff.

       “A Typesetter‐independent TROFF” by Brian W. Kernighan, 1982, AT&T Bell
       Laboratories  Computing Science Technical Report No. 97, provides addi‐
       tional insights into the device and font description file  formats  and
       output format.

       groff(1), groff(7), roff(7)

groff 1.23.0                      2 July 2023                    groff_diff(7)
───────────────────────────────────────────────────────────────────────────────
groff_hdtbl(7)         Miscellaneous Information Manual         groff_hdtbl(7)

Name
       groff_hdtbl - Heidelberger table macros for GNU roff

Description
       The  hdtbl  macros consist of four base and three optional macros, con‐
       trolled by about twenty arguments.  The syntax is simple and similar to
       the HTML table model and nearly as flexible: you can write sequences of
       tokens (macro calls with their arguments and content  data),  separated
       by  blanks  and  beginning with a macro call, into the same line to get
       compact and cleanly arrranged input.  An advantage of hdtbl is that the
       tables are constructed without calling a preprocessor; this means  that
       groff(7)’s  full  macro capabilities are available.  On the other hand,
       table processing with hdtbl is much slower than using the  tbl(1)  pre‐
       processor.   A  further advantage is that the HTML‐like syntax of hdtbl
       will be easily converted to HTML; this is not implemented yet.

Usage
       In this and the next section, we present examples to help users  under‐
       stand  the  basic  workflow  of hdtbl.  First of all, you must load the
       hdtbl.tmac file.  As with nearly all other groff macro packages,  there
       are two possibilities to do so: Either add the line

              .mso hdtbl.tmac

       to  your roff file before using any macros of the hdtbl package, or add
       the option

              -m hdtbl

       to the command line of groff (before the document file  which  contains
       hdtbl  macros).   Then  you can include on or more tables in your docu‐
       ment, where each one must be started and ended with the .TBL  and  .ETB
       macros, respectively.

       In this man page, we approximate the result of each example as terminal
       output to be as generic as possible since hdtbl currently only supports
       the ps and pdf output drivers.

       The  simplest  well‐formed  table  consists of just single calls to the
       four base table macros in the right order.  Here we construct  a  table
       with only one cell.

              .TBL
              .TR
              .TD
              contents of the table cell
              .ETB

       A terminal representation is

              +------------------------------------------------------+
              | contents-of-the-table-cell                           |
              +------------------------------------------------------+

       Equivalent to the above is the following notation.

              .TBL .TR .TD "contents of the table cell" .ETB

       By  default,  the formatted table is inserted into the surrounding text
       at the place of its definition.  If the  vertical  space  isn’t  suffi‐
       cient,  it  is  placed at the top of the next page.  Tables can also be
       stored for later insertion.

       Using ‘row‐number*column‐number’ as the data for the table cells, a ta‐
       ble with two rows and two columns can be written as

              .TBL cols=2
              .  TR .TD 1*1 .TD 1*2
              .  TR .TD 2*1 .TD 2*2
              .ETB

       A terminal representation is

              +--------------------------+---------------------------+
              | 1*1                      | 1*2                       |
              +--------------------------+---------------------------+
              | 2*1                      | 2*2                       |
              +--------------------------+---------------------------+

       Here we see a difference from HTML tables: The number of  columns  must
       be  explicitly specified using the ‘cols=m’ argument (or indirectly via
       the ‘width’ argument, see below).

       The contents of a table cell is arbitrary; for example, it can  be  an‐
       other  table,  without restriction to the nesting depth.  A given table
       layout can be either constructed with suitably nested  tables  or  with
       proper  arguments  to .TD and .TH, controlling column and row spanning.
       Note, however, that this table

              .TBL
              .  TR
              .    TD
              .      nop 1*1 1*2
              .  TR
              .    TD
              .      TBL cols=2 border=
              .        TR
              .          TD
              .            nop 2*1
              .          TD
              .            nop 2*2
              .      ETB
              .ETB

       and this table

              .TBL cols=2
              .  TR
              .    TD colspan=2
              .      nop 1*1 1*2
              .  TR
              .    TD
              .      nop 2*1
              .    TD
              .      nop 2*2
              .ETB

       are similar but not identical (the use of .nop is  purely  cosmetic  to
       get proper indentation).

       The first table looks like

              +------------------------------------------------------+
              | 1*1 1*2                                              |
              +------------------------------------------------------+
              |                                                      |
              | 2*1                         2*2                      |
              |                                                      |
              +------------------------------------------------------+

       and the second one like

              +------------------------------------------------------+
              | 1*1 1*2                                              |
              +---------------------------+--------------------------+
              | 2*1                       | 2*2                      |
              +---------------------------+--------------------------+

       Here is the latter table in a more compact form.

              .TBL cols=2 .TR ".TD colspan=2" 1*1 1*2
              .            TR .TD 2*1 .TD 2*2 .ETB

       If  a macro has one or more arguments (see below), and it is not start‐
       ing a line, everything belonging to this macro including the macro  it‐
       self must be enclosed in double quotes.

Macros and arguments
       The  order  of macro calls and other tokens follows the HTML model.  In
       the following list, valid predecessors  and  successors  of  all  hdtbl
       macros are given, together with the possible arguments.

       Macro arguments are separated by blanks.  The order of arguments is ar‐
       bitrary; they are of the form

              key=value

       or

              key='value1 [value2 [...]]'

       with  the  only  exception  of the optional argument of the macro .ETB,
       which is the string ‘hold’.  Another possible form is

              "key=value1 [value2 [...]]"

       However, this is limited to the case where the macro is the  first  one
       in the line and not already enclosed in double quotes.

       Argument  values specified below as c are colors predefined by groff or
       colors defined by the user with the .defcolor request.   Argument  val‐
       ues d are decimal numbers with or without decimal point.  Argument val‐
       ues m are natural numbers.  Argument values n are numerical values with
       the usual groff scaling indicators.  Some of the arguments are specific
       to one or two macros, but most of them can be specified with .TBL, .TR,
       .TD, and .TH.  These common arguments are explained in the next subsec‐
       tion.

       Most  of the argument default values can be changed by the user by set‐
       ting corresponding default registers or strings, as listed below.

       .TBL [args]
              Begin a new table.

              predecessor: .TD, .TH, .ETB, cell contents
              successor: .CPTN, .TR
              arguments:
                     border=[n]
                            Thickness   of   the   surrounding   box   border.
                            ‘border=’  (no  value) means neither a surrounding
                            box border nor any horizontal or vertical  separa‐
                            tor  lines  between  the  table  rows  and  cells.
                            ‘border=0’ suppresses the surrounding box  border,
                            but still allows separator lines between cells and
                            rows.
                            Default: ‘border=.1n’ (register ‘t*b’).
                     bc=c   Border color.
                            Default: ‘bc=red4’ (string ‘t*bc’).
                     cols=m Number  of table columns.  This argument is neces‐
                            sary if more than one column is in the  table  and
                            no ‘width’ arguments are present.
                            Default: ‘cols=1’ (register ‘t*cols’).
                     cpd=n  Cell  padding,  i.e.,  the extra space between the
                            cell space border and the cell contents.
                            Default: ‘cpd=.5n’ (register ‘t*cpd’).
                     csp=n  Cell spacing, i.e., the extra  space  between  the
                            table  border  or vertical or horizontal lines be‐
                            tween cells and the cellspace.
                            Default: ‘csp=.5n’ (register ‘t*csp’).
                     tal=l|c|r
                            Horizontal  alignment  of  the  table,  if  it  is
                            smaller than the line width.  ‘tal=l’: left align‐
                            ment.    ‘tal=c’:  centered  alignment.   ‘tal=r’:
                            right alignment.
                            Default: ‘tal=l’ (register ‘t*tal’).
                     width='w1 [w2 [...]]'
                            Widths of table cells.  w1,  w2,  ...  are  either
                            numbers  of  type  n  or  natural numbers with the
                            pseudo‐scaling indicator  ‘%’,  with  the  meaning
                            “percent  of  the  actual  line  length (or column
                            length for inner tables, respectively)”.  If there
                            are less width values than table columns, the last
                            width value is used for the remaining cells.   The
                            argument

                                   width='1.5i 10%'

                            for  example  indicates  that  the first column is
                            1.5 inches wide; the remaining columns  take  1/10
                            of the column length each.
                            Default:  The  table  width  equals the outer line
                            length or column length; the  columns  have  equal
                            widths.
                     height=n
                            Height  of  the table.  If the table with its con‐
                            tents is lower than n, the last row  is  stretched
                            to this value.

       .CPTN [args]
              Text of caption.

              The (optionally numbered) table caption.  .CPTN is optional.

              predecessor: .TBL
              successor: .TR
              arguments:
                     val=t|b
                            Vertical alignment of the table caption.  ‘val=t’:
                            The  caption  is placed above the table.  ‘val=b’:
                            The caption is placed below the table.
                            Default: ‘val=t’ (string ‘t*cptn’).

       .TR [args]
              Begin a new table row.

              predecessor: .TBL, .CPTN, .TD, .TH, .ETB, cell contents
              successor: .TD, .TH
              arguments:
                     height=n
                            The height of the row.  If a cell in  the  row  is
                            higher  than  n,  this value is ignored; otherwise
                            the row height is stretched to n.

       .TD [args [cell contents]]
              Begin a table data cell.
       .TH [args [cell contents]]
              Begin a table header cell.

              Arguments and cell contents can be mixed.  The macro .TH is  not
              really necessary and differs from .TD only in three default set‐
              tings,  similar  to the <TH> and <TD> HTML tags: The contents of
              .TH is horizontally and vertically centered and typeset in bold‐
              face.

              predecessor: .TR, .TD, .TH, .ETB, cell contents
              successor: .TD, .TH, .TR, .ETB, cell contents
              arguments:
                     colspan=m
                            The width of this cell is the sum of the widths of
                            the m cells above and below this row.
                     rowspan=m
                            The height of this cell is the sum of the  heights
                            of the m cells left and right of this column.

                            Remark: Overlapping of column and row spanning, as
                            in  the  following table fragment (the overlapping
                            happens in the second cell in the second row),  is
                            invalid and causes incorrect results.

                                   .TR .TD 1*1 ".TD 1*2 rowspan=2" .TD 1*3
                                   .TR ".TD 2*1 colspan=2"         .TD 2*3

                     A working example for headers and cells with colspan is

                            .TBL cols=3
                            .  TR ".TH colspan=2" header1+2 .TH header3
                            .  TR .TD 1*1 .TD 1*2 .TD 1*3
                            .  TR .TD 2*1 ".TD colspan=2" 2*2+3
                            .ETB

                     This looks like

                            +------------------------------+---------------+
                            |          header1+2           |    header3    |
                            +--------------+---------------+---------------+
                            | 1*1          | 1*2           | 1*3           |
                            +--------------+---------------+---------------+
                            | 2*1          | 2*2+3                         |
                            +--------------+-------------------------------+

                     A working example with rowspan is

                            .TBL cols=3
                            .  TR
                            .  TD 1*1
                            .  TD rowspan=2 1+2*2
                            .  TD 1*3
                            .
                            .  TR
                            .  TD 2*1
                            .  TD 2*3
                            .ETB

                     which looks like

                            +--------------+---------------+---------------+
                            | 1*1          | 1+2*2         | 1*3           |
                            +--------------+               +---------------+
                            | 2*1          |               | 2*3           |
                            +--------------+---------------+---------------+

       .ETB [hold]
              End of the table.

              This macro finishes a table.  It causes one of the following ac‐
              tions.

              •  If  the  argument ‘hold’ is given, the table is held until it
                 is freed by calling the macro .t*free, which in  turn  prints
                 the  table  immediately, either at the current position or at
                 the top of the next page if its height is larger than the re‐
                 maining space on the page.

              •  Otherwise, if the table is higher than the remaining space on
                 the page, it is printed at the top of the next page.

              •  If neither of the two above constraints hold,  the  table  is
                 printed immediately at the place of its definition.

              predecessor: .TD, .TH, .ETB, cell contents
              successor: .TBL, .TR, .TD, .TH, .ETB, cell contents
              arguments:
                     hold   Prevent  the  table from being printed until it is
                            freed by calling the macro .t*free.  This argument
                            is ignored for inner (nested) tables.

       .t*free [n]
              Free the next held table or n held tables.   Call  this  utility
              macro  to  print tables which are held by using the ‘hold’ argu‐
              ment of the .ETB macro.

   Arguments common to .TBL, .TR, .TD, and .TH
       The arguments described in this section can be specified with the  .TBL
       and  .TR  macros, but they are eventually passed on to the table cells.
       If omitted, the defaults take place, which the user can change by  set‐
       ting  the corresponding default registers or strings, as documented be‐
       low.  Setting an argument with the .TBL macro has the  same  effect  as
       setting  it  for all rows in the table.  Setting an argument with a .TR
       macro has the same effect as setting it for all the .TH or .TD macro in
       this row.

       bgc=[c]
              The background color of the table cells.  This includes the area
              specified with the ‘csp’  argument.   The  argument  ‘bgc=’  (no
              value)  suppresses a background color; this makes the background
              transparent.
              Default: ‘bgc=bisque’ (string ‘t*bgc’).
       fgc=c  The foreground color of the cell contents.
              Default: ‘fgc=red4’ (string ‘t*fgc’).
       ff=name
              The font family for the table.  name  is  a  groff  font  family
              identifier,  such  as A for Avant Garde or HN for Helvetica Nar‐
              row.
              Default: The font family found before the table (string ‘t*ff’).
       fst=style
              The font style for the table.  One of R, B, I, or BI for  roman,
              bold,  italic, or bold italic, respectively.  As with roff’s .ft
              request, the ‘fst’ argument can be used to specify the font fam‐
              ily and font style together, for example ‘fst=HNBI’  instead  of
              ‘ff=HN’ and ‘fst=BI’.
              Default:  The  font  style in use right before the table (string
              ‘t*fst’).
       fsz='d1 [d2]'
              A decimal or fractional factor d1, by which the point  size  for
              the table is changed, and d2, by which the vertical line spacing
              is changed.  If d2 is omitted, value d1 is taken for both.
              Default: ‘fsz='1.0 1.0'’ (string ‘t*fsz’).
       hal=l|c|b|r
              Horizontal   alignment  of  the  cell  contents  in  the  table.
              ‘hal=l’: left alignment.  ‘hal=c’: centered alignment.  ‘hal=b’:
              both (left and right) alignment.  ‘hal=r’: right alignment.
              Default: ‘hal=b’ (string ‘t*hal’).
       val=t|m|b
              Vertical alignment of the cell contents in the table  for  cells
              lower than the current row.  ‘val=t’: alignment below the top of
              the  cell.   ‘val=m’:  alignment  in  the  middle  of  the cell.
              ‘val=b’: alignment above the cell bottom.
              Default: ‘val=t’ (string ‘t*val’).
       hl=[s|d]
              Horizontal line between the rows.  If specified with .TD or  .TH
              this  is  a separator line to the cell below.  ‘hl=’ (no value):
              no separator line.  ‘hl=s’: a single separator line between  the
              rows.  ‘hl=d’: a double separator line.

              The  thickness  of the separator lines is the half of the border
              thickness, but at least 0.1 inches.  The  distance  between  the
              double lines is equal to the line thickness.

              Remark: Together with ‘border=0’ for proper formatting the value
              of  ‘csp’ must be at least .05 inches for single separator lines
              and .15 inches for double separator lines.
              Default: ‘hl=s’ (string ‘t*hl’).
       vl=[s|d]
              Vertical separator line between the cells.   If  specified  with
              .TD  or  .TH  this is a separator line to the cell on the right.
              ‘vl=s’: a single separator line between the  cells.   ‘vl=d’:  a
              double separator line.  ‘vl=’ (no value): no vertical cell sepa‐
              rator  lines.  For more information see the documentation of the
              ‘hl’ argument above.
              Default: ‘vl=s’ (string ‘t*vl’).

hdtbl customization
       Before creating the first table, you should configure default values to
       minimize the markup needed in each table.  The following  example  sets
       up defaults suitable for typical papers:

              .ds t*bgc white\" background color
              .ds t*fgc black\" foreground color
              .ds t*bc black\"  border color
              .nr t*cpd 0.1n\"  cell padding

       The  file  /usr/share/doc/groff-1.23.0/examples/hdtbl/common.roff  pro‐
       vides another example setup in the “minimal Page setup” section.

       A table which does not fit on a partially filled page is printed  auto‐
       matically  on the top of the next page if you append the little utility
       macro t*hm to the page header macro of your document’s main macro pack‐
       age.  For example, say

              .am pg@top
              .  t*hm
              ..

       if you use the ms macro package.

       The macro t*EM checks for held or kept  tables,  and  for  missing  ETB
       macros (table not closed).  You can call this macro by appending it the
       to  end‐of‐input  macro  of  the main, or “full‐service”, macro package
       your document uses.  For example, try
              .am pg@end-text
              .  t*EM
              ..
       if you use the ms package.

Bugs and suggestions
       Please send your comments to the groff mailing list ⟨groff@gnu.org⟩  or
       directly to the author.

Authors
       The  hdtbl  macro  package  was  written  by Joachim Walsdorff ⟨Joachim
       .Walsdorff@urz.uni-heidelberg.de⟩.

See also
       groff(1)
              provides an overview of GNU roff and details how to invoke groff
              at the command line.

       groff(7)
              summarizes the roff language and GNU extensions to it.

       tbl(1) describes the traditional roff preprocessor for tables.

groff 1.23.0                      2 July 2023                   groff_hdtbl(7)
───────────────────────────────────────────────────────────────────────────────
groff_man(7)           Miscellaneous Information Manual           groff_man(7)

Name
       groff_man - compose manual pages with GNU roff

Synopsis
       groff -man [option ...] [file ...]
       groff -m man [option ...] [file ...]

Description
       The GNU implementation of the man macro package is part  of  the  groff
       document  formatting  system.   It  is  used  to  produce  manual pages
       (“man pages”) like the one you are reading.

       This document presents the macros thematically; for those needing  only
       a  quick reference, the following table lists them alphabetically, with
       cross references to appropriate subsections below.

       Man page authors and maintainers who are not already experienced  groff
       users  should  consult  groff_man_style(7), an expanded version of this
       document, for additional explanations and advice.  It covers only those
       concepts required for man page document maintenance, and not  the  full
       breadth of the groff typesetting system.

       Macro   Meaning                      Subsection
       ───────────────────────────────────────────────────────────────
       .B      Bold                         Font style macros
       .BI     Bold, italic alternating     Font style macros
       .BR     Bold, roman alternating      Font style macros
       .EE     Example end                  Document structure macros
       .EX     Example begin                Document structure macros
       .I      Italic                       Font style macros
       .IB     Italic, bold alternating     Font style macros
       .IP     Indented paragraph           Paragraphing macros
       .IR     Italic, roman alternating    Font style macros
       .LP     Begin paragraph              Paragraphing macros
       .ME     Mail‐to end                  Hyperlink macros
       .MR     Man page cross reference     Hyperlink macros
       .MT     Mail‐to start                Hyperlink macros
       .P      Begin paragraph              Paragraphing macros
       .PP     Begin paragraph              Paragraphing macros
       .RB     Roman, bold alternating      Font style macros
       .RE     Relative inset end           Document structure macros
       .RI     Roman, italic alternating    Font style macros
       .RS     Relative inset start         Document structure macros
       .SB     Small bold                   Font style macros
       .SH     Section heading              Document structure macros
       .SM     Small                        Font style macros
       .SS     Subsection heading           Document structure macros
       .SY     Synopsis start               Command synopsis macros
       .TH     Title heading                Document structure macros
       .TP     Tagged paragraph             Paragraphing macros
       .TQ     Supplemental paragraph tag   Paragraphing macros
       .UE     URI end                      Hyperlink macros
       .UR     URI start                    Hyperlink macros
       .YS     Synopsis end                 Command synopsis macros

       We  discuss  other macros (.AT, .DT, .HP, .OP, .PD, and .UC) in subsec‐
       tion “Deprecated features” below.

       Throughout Unix documentation, a manual entry is referred to simply  as
       a  “man  page”, regardless of its length, without gendered implication,
       and irrespective of the macro package selected for its composition.

   Macro reference preliminaries
       A tagged paragraph describes each macro.  We present coupled pairs  to‐
       gether, as with .EX and .EE.

       An  empty  macro argument can be specified with a pair of double‐quotes
       (""), but the man package is designed such that this should  seldom  be
       necessary.   Most macro arguments will be formatted as text in the out‐
       put; exceptions are noted.

   Document structure macros
       Document structure macros organize a man page’s content.  All  of  them
       break  the output line.  .TH (title heading) identifies the document as
       a man page and configures the page headers and footers.  Section  head‐
       ings (.SH), one of which is mandatory and many of which are convention‐
       ally  expected,  facilitate  location of material by the reader and aid
       the man page writer to discuss all  essential  aspects  of  the  topic.
       Subsection  headings  (.SS)  are optional and permit sections that grow
       long to develop in a controlled way.  Many technical discussions  bene‐
       fit  from  examples; lengthy ones, especially those reflecting multiple
       lines of input to or output from the system, are usefully bracketed  by
       .EX and .EE.  When none of the foregoing meets a structural demand, use
       .RS/.RE to inset a region within a (sub)section.

       .TH topic section [footer‐middle] [footer‐inside] [header‐middle]
              Determine  the contents of the page header and footer.  The sub‐
              ject of the man page is topic and the section of the  manual  to
              which  it  belongs  is  section.  See man(1) or intro(1) for the
              manual sectioning applicable to your system.  topic and  section
              are  positioned  together  at  the  left and right in the header
              (with section in parentheses  immediately  appended  to  topic).
              footer‐middle is centered in the footer.  The arrangement of the
              rest of the footer depends on whether double‐sided layout is en‐
              abled  with  the  option  -rD1.   When  disabled  (the default),
              footer‐inside is positioned  at  the  bottom  left.   Otherwise,
              footer‐inside appears at the bottom left on recto (odd‐numbered)
              pages,  and  at the bottom right on verso (even‐numbered) pages.
              The outside footer is the page number, except in the continuous‐
              rendering mode enabled by the option -rcR=1, in which case it is
              the topic and section, as in the header.  header‐middle is  cen‐
              tered  in  the header.  If section is an integer between 1 and 9
              (inclusive), there is no need to specify header‐middle;  an.tmac
              will  supply text for it.  The macro package may also abbreviate
              topic and footer‐inside with ellipses if they would overrun  the
              space  available  in  the  header and footer, respectively.  For
              HTML output, headers and footers are suppressed.

              Additionally, this macro breaks the page, resetting  the  number
              to  1  (unless  the  -rC1 option is given).  This feature is in‐
              tended only for formatting multiple man documents in sequence.

              A valid man document calls .TH once, early in the file, prior to
              any other macro calls.

       .SH [heading‐text]
              Set heading‐text as a section heading.  If no argument is given,
              a one‐line input trap is planted; text on the next line  becomes
              heading‐text.  The left margin is reset to zero to set the head‐
              ing  text in bold (or the font specified by the string HF), and,
              on typesetting devices, slightly larger than the base type size.
              If the heading font \*[HF] is bold, use of an  italic  style  in
              heading‐text  is mapped to the bold‐italic style if available in
              the font family.  The inset level is reset  to  1,  setting  the
              left  margin  to the value of the IN register.  Text after head‐
              ing‐text is set as an ordinary paragraph (.P).

              The content of heading‐text and ordering of sections  follows  a
              set  of  common practices, as has much of the layout of material
              within sections.  For example, a section called “Name” or “NAME”
              must exist, must be the first section after the  .TH  call,  and
              must contain only text of the form
                     topic[, another‐topic]... \- summary‐description
              for  a  man page to be properly indexed.  See groff_man_style(7)
              for suggestions and man(7) for  the  conventions  prevailing  on
              your system.

       .SS [subheading‐text]
              Set  subheading‐text  as a subsection heading indented between a
              section heading and an ordinary paragraph (.P).  If no  argument
              is  given,  a  one‐line  input trap is planted; text on the next
              line becomes subheading‐text.  The left margin is reset  to  the
              value of the SN register to set the heading text in bold (or the
              font specified by the string HF).  If the heading font \*[HF] is
              bold, use of an italic style in subheading‐text is mapped to the
              bold‐italic  style  if  available in the font family.  The inset
              level is reset to 1, setting the left margin to the value of the
              IN register.  Text after subheading‐text is set as  an  ordinary
              paragraph (.P).

       .EX
       .EE    Begin  and  end  example.   After .EX, filling is disabled and a
              constant‐width (monospaced) font is selected.  Calling  .EE  en‐
              ables filling and restores the previous font.

              These macros are extensions introduced in Ninth Edition Research
              Unix.   Systems  running  that troff, or those from Documenter’s
              Workbench, Heirloom Doctools, or Plan 9 troff support them.   To
              be  certain  your  page will be portable to systems that do not,
              copy their definitions from the an-ext.tmac file of a groff  in‐
              stallation.

       .RS [inset‐amount]
              Start a new relative inset level.  The position of the left mar‐
              gin  is  saved,  then moved right by inset‐amount, if specified,
              and by the amount of the IN register otherwise.   Calls  to  .RS
              can be nested; each increments by 1 the inset level used by .RE.
              The level prior to any .RS calls is 1.

       .RE [level]
              End  a  relative  inset.  The left margin corresponding to inset
              level level is restored.  If no argument  is  given,  the  inset
              level is reduced by 1.

   Paragraphing macros
       An  ordinary  paragraph (.P) is set without a first‐line indentation at
       the current left margin.  In man pages and other technical  literature,
       definition  lists  are  frequently  encountered;  these  can  be set as
       “tagged paragraphs”, which have one (.TP) or more  (.TQ)  leading  tags
       followed  by  a  paragraph that has an additional indentation.  The in‐
       dented paragraph (.IP) macro is useful to continue the indented content
       of a narrative started with .TP, or to present an itemized  or  ordered
       list.  All of these macros break the output line.  If another paragraph
       macro has occurred since the previous .SH or .SS, they (except for .TQ)
       follow  the break with a default amount of vertical space, which can be
       changed by the deprecated .PD macro;  see  subsection  “Horizontal  and
       vertical  spacing” below.  They also reset the type size and font style
       to defaults (.TQ again excepted); see subsection  “Font  style  macros”
       below.

       .P
       .LP
       .PP    Begin  a new paragraph; these macros are synonymous.  The inden‐
              tation is reset to the default value; the left  margin,  as  af‐
              fected by .RS and .RE, is not.

       .TP [indentation]
              Set  a  paragraph  with  a leading tag, and the remainder of the
              paragraph indented.  A one‐line input trap is planted;  text  on
              the  next line, which can be formatted with a macro, becomes the
              tag, which is placed at the current left margin.  The tag can be
              extended with the \c escape sequence.  Subsequent  text  is  in‐
              dented by indentation, if specified, and by the amount of the IN
              register  otherwise.   If the tag is not as wide as the indenta‐
              tion, the paragraph starts on the same line as the tag,  at  the
              applicable  indentation,  and  continues on the following lines.
              Otherwise, the descriptive part of the paragraph begins  on  the
              line following the tag.

       .TQ    Set an additional tag for a paragraph tagged with .TP.  An input
              trap is planted as with .TP.

              This  macro  is  a  GNU extension not defined on systems running
              AT&T, Plan 9, or  Solaris  troff;  see  an-ext.tmac  in  section
              “Files” below.

       .IP [tag] [indentation]
              Set an indented paragraph with an optional tag.  The tag and in‐
              dentation  arguments,  if present, are handled as with .TP, with
              the exception that the tag argument  to  .IP  cannot  include  a
              macro call.

   Command synopsis macros
       .SY  and .YS aid you to construct a command synopsis that has the clas‐
       sical Unix appearance.  They break the output line.

       These macros are GNU extensions not defined on  systems  running  AT&T,
       Plan 9, or Solaris troff; see an-ext.tmac in section “Files” below.

       .SY command
              Begin  synopsis.   A new paragraph begins at the left margin un‐
              less .SY has already been called without a corresponding .YS, in
              which case only a break is performed.  Adjustment and  automatic
              hyphenation  are  disabled.  command is set in bold.  If a break
              is required, lines after the first are indented by the width  of
              command plus a space.

       .YS    End  synopsis.  Indentation, adjustment, and hyphenation are re‐
              stored to their previous states.

   Hyperlink macros
       Man page cross references are best presented with .MR.  Text may be hy‐
       perlinked to email addresses with .MT/.ME or other URIs  with  .UR/.UE.
       Hyperlinked text is supported on HTML and terminal output devices; ter‐
       minals  and  pager programs must support ECMA‐48 OSC 8 escape sequences
       (see grotty(1)).  When device support is unavailable or  disabled  with
       the U register (see section “Options” below), .MT and .UR URIs are ren‐
       dered between angle brackets after the linked text.

       .MT,  .ME,  .UR, and .UE are GNU extensions not defined on systems run‐
       ning AT&T, Plan 9, or Solaris troff; see an-ext.tmac in section “Files”
       below.  Plan 9 from User Space’s troff implements .MR.

       The arguments to .MR, .MT, and .UR should be prepared  for  typesetting
       since  they can appear in the output.  Use special character escape se‐
       quences to encode Unicode basic Latin characters where necessary,  par‐
       ticularly  the hyphen‐minus.  The formatter removes \: escape sequences
       from hyperlinks when supplying device control commands to  output  dri‐
       vers.

       .MR topic manual‐section [trailing‐text]
              (since groff 1.23) Set a man page cross reference as “topic(man‐
              ual‐section)”.   If  trailing‐text  (typically  punctuation)  is
              specified, it follows the closing parenthesis without  interven‐
              ing space.  Hyphenation is disabled while the cross reference is
              set.   topic is set in the font specified by the MF string.  The
              cross reference hyperlinks to a URI of the form  “man:topic(man‐
              ual‐section)”.

       .MT address
       .ME [trailing‐text]
              Identify  address  as  an RFC 6068 addr‐spec for a “mailto:” URI
              with the text between the two macro calls as the link text.   An
              argument  to .ME is placed after the link text without interven‐
              ing space.  address may not be visible in the rendered  document
              if  hyperlinks  are  enabled and supported by the output driver.
              If they are not, address is set in angle brackets after the link
              text and before trailing‐text.  If hyperlinking is  enabled  but
              there  is  no  link  text,  address is formatted and hyperlinked
              without angle brackets.

       .UR uri
       .UE [trailing‐text]
              Identify uri as an RFC 3986 URI hyperlink with the text  between
              the  two  macro  calls  as the link text.  An argument to .UE is
              placed after the link text without intervening space.   uri  may
              not  be  visible  in the rendered document if hyperlinks are en‐
              abled and supported by the output driver.  If they are not,  uri
              is  set  in angle brackets after the link text and before trail‐
              ing‐text.  If hyperlinking is enabled but there is no link text,
              uri is formatted and hyperlinked without angle brackets.

       The hyperlinking of .TP paragraph tags with .UR/.UE and .MT/.ME is  not
       yet  supported;  if attempted, the hyperlink will be typeset at the be‐
       ginning of the indented paragraph even on hyperlink‐supporting devices.

   Font style macros
       The man macro package is limited in its font styling options,  offering
       only bold (.B), italic (.I), and roman.  Italic text is usually set un‐
       derscored instead on terminal devices.  The .SM and .SB macros set text
       in  roman  or  bold, respectively, at a smaller type size; these differ
       visually from regular‐sized roman or bold text only on typesetting  de‐
       vices.   It  is often necessary to set text in different styles without
       intervening space.  The macros .BI, .BR, .IB, .IR, .RB, and .RI,  where
       “B”,  “I”,  and “R” indicate bold, italic, and roman, respectively, set
       their odd‐ and even‐numbered arguments in alternating styles,  with  no
       space separating them.

       The  default  type  size and family for typesetting devices is 10‐point
       Times, except on the X75-12 and X100-12 devices where the type size  is
       12 points.  The default style is roman.

       .B [text]
              Set  text  in  bold.   If no argument is given, a one‐line input
              trap is planted; text on the next line,  which  can  be  further
              formatted with a macro, is set in bold.

       .I [text]
              Set text in an italic or oblique face.  If no argument is given,
              a  one‐line  input trap is planted; text on the next line, which
              can be further formatted with a macro, is set in  an  italic  or
              oblique face.

       .SM [text]
              Set  text  one point smaller than the default type size on type‐
              setting devices.  If no argument is given, a one‐line input trap
              is planted; text on the next line, which can be further  format‐
              ted with a macro, is set smaller.

       .SB [text]
              Set  text in bold and (on typesetting devices) one point smaller
              than the default type size.  If no argument is given, a one‐line
              input trap is planted; text on the next line, which can be  fur‐
              ther  formatted  with a macro, is set smaller and in bold.  This
              macro is an extension introduced in SunOS 4.0.

       Unlike the above font style macros, the font style  alternation  macros
       below  set no input traps; they must be given arguments to have effect.
       Italic corrections are applied as appropriate.

       .BI bold‐text italic‐text ...
              Set each argument in bold and italics, alternately.

       .BR bold‐text roman‐text ...
              Set each argument in bold and roman, alternately.

       .IB italic‐text bold‐text ...
              Set each argument in italics and bold, alternately.

       .IR italic‐text roman‐text ...
              Set each argument in italics and roman, alternately.

       .RB roman‐text bold‐text ...
              Set each argument in roman and bold, alternately.

       .RI roman‐text italic‐text ...
              Set each argument in roman and italics, alternately.

   Horizontal and vertical spacing
       The indentation argument accepted by .IP, .TP, and the  deprecated  .HP
       is  a  number  plus an optional scaling unit, as is .RS’s inset‐amount.
       If no scaling unit is given, the man package assumes “n”.  An  indenta‐
       tion  specified  in  a call to .IP, .TP, or the deprecated .HP persists
       until (1) another of these macros is called with an  indentation  argu‐
       ment, or (2) .SH, .SS, or .P or its synonyms is called; these clear the
       indentation entirely.

       The  left  margin used by ordinary paragraphs set with .P (and its syn‐
       onyms) not within an .RS/.RE relative inset is 7.2n for typesetting de‐
       vices and 7n for terminal devices (but see the -rIN option).   Headers,
       footers  (both set with .TH), and section headings (.SH) are set at the
       page offset (see groff(7)) and subsection headings (.SS) indented  from
       it by 3n (but see the -rSN option).

       Several  macros  insert vertical space: .SH, .SS, .TP, .P (and its syn‐
       onyms), .IP, and the deprecated .HP.  The default inter‐section and in‐
       ter‐paragraph spacing is is 1v for terminal devices and 0.4v for  type‐
       setting  devices.   (The  deprecated macro .PD can change this vertical
       spacing, but its use is discouraged.)  Between .EX and .EE  calls,  the
       inter‐paragraph spacing is 1v regardless of output device.

   Registers
       Registers  are  described  in section “Options” below.  They can be set
       not only on the command line but in the site man.local  file  as  well;
       see section “Files” below.

   Strings
       The  following strings are defined for use in man pages.  None of these
       is necessary in a contemporary man page; see groff_man_style(7).   Oth‐
       ers  are  supported for configuration of rendering parameters; see sec‐
       tion “Options” below.

       \*R    interpolates a special character escape sequence for the “regis‐
              tered sign” glyph, \(rg, if available, and “(Reg.)” otherwise.

       \*S    interpolates an escape sequence setting the  type  size  to  the
              document default.

       \*(lq
       \*(rq  interpolate  special  character  escape  sequences  for left and
              right double‐quotation marks, \(lq and \(rq, respectively.

       \*(Tm  interpolates a special character escape sequence for the  “trade
              mark sign” glyph, \(tm, if available, and “(TM)” otherwise.

   Hooks
       Two macros, both GNU extensions, are called internally by the groff man
       package  to format page headers and footers and can be redefined by the
       administrator in a site’s man.local file (see section  “Files”  below).
       The  presentation  of .TH above describes the default headers and foot‐
       ers.  Because these macros are hooks for groff man internals, man pages
       have no reason to call them.  Such hook definitions will likely consist
       of “.sp” and “.tl” requests.  They must also increase the  page  length
       with  “.pl”  requests in continuous rendering mode; .PT furthermore has
       the responsibility of emitting a PDF bookmark after writing  the  first
       page  header  in  a  document.  Consult the existing implementations in
       an.tmac when drafting replacements.

       .BT    Set the page footer text (“bottom trap”).

       .PT    Set the page header text (“page trap”).

       To remove a page header or  footer  entirely,  define  the  appropriate
       macro as empty rather than deleting it.

   Deprecated features
       Use  of  the following in man pages for public distribution is discour‐
       aged.

       .AT [system [release]]
              Alter the footer for use with legacy AT&T man pages,  overriding
              any definition of the footer‐inside argument to .TH.  This macro
              exists only to render man pages from historical systems.

              system can be any of the following.

                     3      7th edition (default)

                     4      System III

                     5      System V

              The  optional  release argument specifies the release number, as
              in “System V Release 3”.

       .DT    Reset tab stops to the default (every 0.5i).

              Use of  this  presentation‐oriented  macro  is  deprecated.   It
              translates  poorly  to HTML, under which exact space control and
              tabulation are not readily available.  Thus, information or dis‐
              tinctions that you use tab stops to express  are  likely  to  be
              lost.   If  you  feel  tempted to change the tab stops such that
              calling this macro later  is  desirable  to  restore  them,  you
              should probably be composing a table using tbl(1) instead.

       .HP [indentation]
              Set  up a paragraph with a hanging left indentation.  The inden‐
              tation argument, if present, is handled as with .TP.

              Use of this presentation‐oriented macro is deprecated.  A  hang‐
              ing  indentation  cannot  be expressed naturally under HTML, and
              non‐roff‐based man page interpreters may treat .HP as  an  ordi‐
              nary  paragraph.   Thus, information or distinctions you mean to
              express with indentation may be lost.

       .OP option‐name [option‐argument]
              Indicate an optional command parameter called option‐name, which
              is set in bold.  If the option takes an  argument,  specify  op‐
              tion‐argument  using  a  noun,  abbreviation, or hyphenated noun
              phrase.  If present, option‐argument is preceded by a space  and
              set  in  italics.   Square brackets in roman surround both argu‐
              ments.

              Use of this quasi‐semantic macro, an  extension  originating  in
              Documenter’s  Workbench  troff, is deprecated.  It cannot easily
              be used to annotate options that take optional arguments or  op‐
              tions whose arguments have internal structure (such as a mixture
              of  literal  and  variable  components).   One could work around
              these limitations with font selection escape sequences,  but  it
              is preferable to use font style alternation macros, which afford
              greater flexibility.

       .PD [vertical‐space]
              Define  the  vertical space between paragraphs or (sub)sections.
              The optional argument vertical‐space specifies the  amount;  the
              default  scaling  unit is “v”.  Without an argument, the spacing
              is reset to its default value; see  subsection  “Horizontal  and
              vertical spacing” above.

              Use  of  this  presentation‐oriented  macro  is  deprecated.  It
              translates poorly to HTML, under which exact control  of  inter‐
              paragraph  spacing  is not readily available.  Thus, information
              or distinctions that you use .PD to express  are  likely  to  be
              lost.

       .UC [version]
              Alter  the  footer for use with legacy BSD man pages, overriding
              any definition of the footer‐inside argument to .TH.  This macro
              exists only to render man pages from historical systems.

              version can be any of the following.

                     3      3rd Berkeley Distribution (default)

                     4      4th Berkeley Distribution

                     5      4.2 Berkeley Distribution

                     6      4.3 Berkeley Distribution

                     7      4.4 Berkeley Distribution

   History
       M. Douglas McIlroy ⟨m.douglas.mcilroy@dartmouth.edu⟩  designed,  imple‐
       mented,  and  documented  the AT&T man macros for Unix Version 7 (1979)
       and employed them to edit the first volume of its Programmer’s  Manual,
       a  compilation  of all man pages supplied by the system.  That man sup‐
       ported the macros listed in this page not described as extensions,  ex‐
       cept  .P and the deprecated .AT and .UC.  The only strings defined were
       R and S; no registers were documented.

       .UC appeared in 3BSD (1980).  Unix System III (1980) introduced .P  and
       exposed  the  registers  IN  and LL, which had been internal to Seventh
       Edition Unix man.  PWB/UNIX 2.0  (1980)  added  the  Tm  string.   4BSD
       (1980)  added  lq and rq strings.  SunOS 2.0 (1985) recognized C, D, P,
       and X registers.  4.3BSD (1986) added .AT and .P.   Ninth  Edition  Re‐
       search Unix (1986) introduced .EX and .EE.  SunOS 4.0 (1988) added .SB.

       The  foregoing features were what James Clark implemented in early ver‐
       sions of groff.  Later, groff  1.20  (2009)  originated  .SY/.YS,  .TQ,
       .MT/.ME, and .UR/.UE.  Plan 9 from User Space’s troff introduced .MR in
       2020.

Options
       The  following  groff options set registers (with -r) and strings (with
       -d) recognized and used by the man macro package.  To ensure  rendering
       consistent  with output device capabilities and reader preferences, man
       pages should never manipulate them.

       -dAD=adjustment‐mode
              Set line adjustment to adjustment‐mode, which is  typically  “b”
              for  adjustment  to  both margins (the default), or “l” for left
              alignment (ragged right margin).  Any valid argument to  groff’s
              “.ad”  request  may  be  used.   See  groff(7)  for  less‐common
              choices.

       -rcR=1 Enable continuous rendering.  Output is not paginated;  instead,
              one  (potentially  very long) page is produced.  This is the de‐
              fault for terminal and HTML devices.  Use -rcR=0 to  disable  it
              on terminal devices; on HTML devices, it cannot be disabled.

       -rC1   Number  output  pages  consecutively, in strictly increasing se‐
              quence, rather than resetting the page number to 1 (or the value
              of register P) with each new man document.

       -rCS=1 Set section headings (the argument(s) to .SH) in full  capitals.
              This  transformation  is off by default because it discards case
              distinction information.

       -rCT=1 Set the man page topic (the first argument to .TH) in full capi‐
              tals in headers and footers.  This transformation is off by  de‐
              fault because it discards case distinction information.

       -rD1   Enable  double‐sided layout, formatting footers for even and odd
              pages differently; see the  description  of  .TH  in  subsection
              “Document structure macros” above.

       -rFT=footer‐distance
              Set distance of the footer relative to the bottom of the page to
              footer‐distance;  this  amount is always negative.  At one half‐
              inch above this location, the page text is broken before writing
              the footer.  Ignored if continuous rendering  is  enabled.   The
              default is -0.5i.

       -dHF=heading‐font
              Set  the  font used for section and subsection headings; the de‐
              fault is “B” (bold style of the default family).  Any valid  ar‐
              gument to groff’s “.ft” request may be used.  See groff(7).

       -rHY=0 Disable  automatic  hyphenation.   Normally,  it is enabled (1).
              The hyphenation mode is determined by the groff locale; see sec‐
              tion “Localization“ of groff(7).

       -rIN=standard‐indentation
              Set the amount of indentation used for ordinary  paragraphs  (.P
              and  its  synonyms)  and  the default indentation amount used by
              .IP, .RS, .TP, and the deprecated .HP.  See subsection “Horizon‐
              tal and vertical spacing” above for the default.   For  terminal
              devices, standard‐indentation should always be an integer multi‐
              ple of unit “n” to get consistent indentation.

       -rLL=line‐length
              Set  line  length;  the  default is 78n for terminal devices and
              6.5i for typesetting devices.

       -rLT=title‐length
              Set the line length for titles.  By default, it is  set  to  the
              line length (see -rLL above).

       -dMF=man‐page‐topic‐font
              Set  the  font  used  for  man  page topics named in .TH and .MR
              calls; the default is “I” (italic style of the default  family).
              Any valid argument to groff’s “.ft” request may be used.  If the
              MF  string ends in “I”, it is assumed to be an oblique typeface,
              and italic corrections are applied before  and  after  man  page
              topics.

       -rPn   Start enumeration of pages at n.  The default is 1.

       -rStype‐size
              Use  type‐size  for  the document’s body text; acceptable values
              are 10, 11, or 12 points.  See subsection  “Font  style  macros”
              above for the default.

       -rSN=subsection‐indentation
              Set  indentation  of  subsection headings to subsection‐indenta‐
              tion.  See subsection “Horizontal and  vertical  spacing”  above
              for the default.

       -rU1   Enable  generation  of  URI hyperlinks in the grohtml and grotty
              output drivers.  grohtml enables them by  default;  grotty  does
              not,  pending more widespread pager support for OSC 8 escape se‐
              quences.  Use -rU0 to disable hyperlinks; this will make the ar‐
              guments to MT and UR calls visible in the document text produced
              by link‐capable drivers.

       -rXp   Number successors of page p as pa, pb, pc, and  so  forth.   The
              register  tracking the suffixed page letter uses format “a” (see
              the “.af” request in groff(7)).

Files
       /usr/share/groff/1.23.0/tmac/an.tmac
              Most man macros are defined in this file.  It also loads  exten‐
              sions from an-ext.tmac (see below).

       /usr/share/groff/1.23.0/tmac/andoc.tmac
              This  brief  groff program detects whether the man or mdoc macro
              package is being used by a document and loads the correct  macro
              definitions,  taking advantage of the fact that pages using them
              must call .TH or .Dd, respectively, before any other macros.   A
              man program or user typing, for example, “groff -mandoc page.1”,
              need  not know which package the file page.1 uses.  Multiple man
              pages, in either format, can  be  handled;  andoc  reloads  each
              macro package as necessary.

       /usr/share/groff/1.23.0/tmac/an-ext.tmac
              Except  for .SB, definitions of macros described above as exten‐
              sions are contained in this file; in some cases, they  are  sim‐
              pler  versions  of definitions appearing in an.tmac, and are ig‐
              nored if the formatter is GNU troff.  They  are  written  to  be
              compatible  with  AT&T troff and permissively licensed—not copy‐
              lefted.  To reduce the risk of name space collisions, string and
              register names begin only with “m”.  We encourage man  page  au‐
              thors who are concerned about portability to legacy Unix systems
              to  copy  these definitions into their pages, and maintainers of
              troff implementations or  work‐alike  systems  that  format  man
              pages to re‐use them.

              The  definitions  for  these  macros are read after a page calls
              .TH, so they will replace any macros of the same names preceding
              it in your file.  If you use your own implementations  of  these
              macros, they must be defined after .TH is called to have any ef‐
              fect.   Furthermore, it is wise to define such page‐local macros
              (if at all) after the “Name” section to accommodate timid  make‐
              whatis  or mandb implementations that may give up their scan for
              indexing material early.

       /usr/share/groff/1.23.0/tmac/man.tmac
              This is a wrapper that loads an.tmac.

       /usr/share/groff/1.23.0/tmac/mandoc.tmac
              This is a wrapper that loads andoc.tmac.

       /usr/share/groff/site-tmac/man.local
              Put site‐local changes and customizations into this file.

Authors
       The initial GNU implementation of the man macro package was written  by
       James  Clark.   Later,  Werner Lemberg ⟨wl@gnu.org⟩ supplied the S, LT,
       and cR registers, the last a 4.3BSD‐Reno mdoc(7) feature.  Larry Kollar
       ⟨kollar@alltel.net⟩ added the FT, HY, and SN registers; the HF  string;
       and  the  PT  and  BT macros.  G. Branden Robinson ⟨g.branden.robinson@
       gmail.com⟩ implemented the AD and MF strings; CS, CT, and U  registers;
       and the MR macro.  Except for .SB, the extension macros were written by
       Lemberg, Eric S. Raymond ⟨esr@thyrsus.com⟩, and Robinson.

       This document was originally written for the Debian GNU/Linux system by
       Susan  G.  Kleinmann ⟨sgk@debian.org⟩.  It was corrected and updated by
       Lemberg and Robinson.  The extension macros were documented by  Raymond
       and Robinson.

See also
       tbl(1),  eqn(1),  and  refer(1)  are preprocessors used with man pages.
       man(1) describes the man page librarian on your system.   groff_mdoc(7)
       details the groff version of the BSD‐originated alternative macro pack‐
       age for man pages.

       groff_man_style(7), groff(7), groff_char(7), man(7)

groff 1.23.0                     16 July 2023                     groff_man(7)
───────────────────────────────────────────────────────────────────────────────
groff_man_style(7)     Miscellaneous Information Manual     groff_man_style(7)

Name
       groff_man_style - GNU roff man page tutorial and style guide

Synopsis
       groff -man [option ...] [file ...]
       groff -m man [option ...] [file ...]

Description
       The  GNU  implementation  of the man macro package is part of the groff
       document formatting  system.   It  is  used  to  produce  manual  pages
       (“man pages”) like the one you are reading.

       This  document presents the macros thematically; for those needing only
       a quick reference, the following table lists them alphabetically,  with
       cross references to appropriate subsections below.

       Macro   Meaning                      Subsection
       ───────────────────────────────────────────────────────────────
       .B      Bold                         Font style macros
       .BI     Bold, italic alternating     Font style macros
       .BR     Bold, roman alternating      Font style macros
       .EE     Example end                  Document structure macros
       .EX     Example begin                Document structure macros
       .I      Italic                       Font style macros
       .IB     Italic, bold alternating     Font style macros
       .IP     Indented paragraph           Paragraphing macros
       .IR     Italic, roman alternating    Font style macros
       .LP     Begin paragraph              Paragraphing macros
       .ME     Mail‐to end                  Hyperlink macros
       .MR     Man page cross reference     Hyperlink macros
       .MT     Mail‐to start                Hyperlink macros
       .P      Begin paragraph              Paragraphing macros
       .PP     Begin paragraph              Paragraphing macros
       .RB     Roman, bold alternating      Font style macros
       .RE     Relative inset end           Document structure macros
       .RI     Roman, italic alternating    Font style macros
       .RS     Relative inset start         Document structure macros
       .SB     Small bold                   Font style macros
       .SH     Section heading              Document structure macros
       .SM     Small                        Font style macros
       .SS     Subsection heading           Document structure macros
       .SY     Synopsis start               Command synopsis macros
       .TH     Title heading                Document structure macros
       .TP     Tagged paragraph             Paragraphing macros
       .TQ     Supplemental paragraph tag   Paragraphing macros
       .UE     URI end                      Hyperlink macros
       .UR     URI start                    Hyperlink macros
       .YS     Synopsis end                 Command synopsis macros

       We  discuss  other macros (.AT, .DT, .HP, .OP, .PD, and .UC) in subsec‐
       tion “Deprecated features” below.

       Throughout Unix documentation, a manual entry is referred to simply  as
       a  “man  page”, regardless of its length, without gendered implication,
       and irrespective of the macro package selected for its composition.

       Man pages should be encoded using Unicode basic Latin code  points  ex‐
       clusively, and employ the Unix line‐ending convention (U+000A only).

   Fundamental concepts
       groff  is  a  programming system for typesetting: we thus often use the
       verb “to set” in the sense “to typeset”.  The formatter  troff(1)  col‐
       lects  words from the input and fills output lines with as many as will
       fit.  Words are separated by spaces and newlines.  A  transition  to  a
       new  output line is called a break.  When formatted, a word may be bro‐
       ken at hyphens, at \% or \: escape sequences (see subsection “Portabil‐
       ity” below), or at predetermined locations if automatic hyphenation  is
       enabled  (see  the  -rHY option in section “Options” below).  An output
       line may be supplemented with inter‐sentence space, and then optionally
       adjusted with more space to a consistent line length (see the -dAD  op‐
       tion).  roff(7) details these processes.

       An input line that starts with a dot (.) or neutral apostrophe (') is a
       control  line.   To call a macro, put its name after a dot on a control
       line.  We refer to macros in this  document  using  this  leading  dot.
       Some  macros  interpret arguments, words that follow the macro name.  A
       newline, unless escaped (see subsection “Portability” below), marks the
       end of the macro call.  An input line consisting of a dot followed by a
       newline is called the empty request; it does nothing.  Text  lines  are
       input lines that are not control lines.

       We  describe  below several man macros that plant one‐line input traps:
       the next input line that directly produces formatted output is  treated
       specially.  For man documents that follow the advice in section “Porta‐
       bility”  below,  this  means that control lines using the empty request
       and uncommented input lines ending  with  an  escaped  newline  do  not
       spring  the  trap;  anything  else does (but see the .TP macro descrip‐
       tion).

   Macro reference preliminaries
       A tagged paragraph describes each macro.  We present coupled pairs  to‐
       gether, as with .EX and .EE.

       Optional  macro arguments are indicated by surrounding them with square
       brackets.  If a macro  accepts  multiple  arguments,  those  containing
       space characters must be double‐quoted to be interpreted correctly.  An
       empty  macro  argument  can  be  specified with a pair of double‐quotes
       (""), but the man package is designed such that this should  seldom  be
       necessary.   See section “Notes” below for examples of cases where bet‐
       ter alternatives to empty arguments in macro calls are available.  Most
       macro arguments will be formatted as text in the output; exceptions are
       noted.

   Document structure macros
       Document structure macros organize a man page’s content.  All  of  them
       break  the output line.  .TH (title heading) identifies the document as
       a man page and configures the page headers and footers.  Section  head‐
       ings (.SH), one of which is mandatory and many of which are convention‐
       ally  expected,  facilitate  location of material by the reader and aid
       the man page writer to discuss all  essential  aspects  of  the  topic.
       Subsection  headings  (.SS)  are optional and permit sections that grow
       long to develop in a controlled way.  Many technical discussions  bene‐
       fit  from  examples; lengthy ones, especially those reflecting multiple
       lines of input to or output from the system, are usefully bracketed  by
       .EX and .EE.  When none of the foregoing meets a structural demand, use
       .RS/.RE to inset a region within a (sub)section.

       .TH topic section [footer‐middle] [footer‐inside] [header‐middle]
              Determine the contents of the page header and footer.  roff sys‐
              tems  refer  to  these collectively as “titles”.  The subject of
              the man page is topic and the section of the manual to which  it
              belongs  is  section.   This  use of “section” has nothing to do
              with the section headings otherwise discussed in this  page;  it
              arises  from the organizational scheme of printed and bound Unix
              manuals.  See man(1) or intro(1) for the manual  sectioning  ap‐
              plicable  to  your system.  topic and section are positioned to‐
              gether at the left and right in  the  header  (with  section  in
              parentheses  immediately  appended  to topic).  footer‐middle is
              centered in the footer.  The arrangement  of  the  rest  of  the
              footer  depends  on  whether double‐sided layout is enabled with
              the option -rD1.  When disabled (the default), footer‐inside  is
              positioned at the bottom left.  Otherwise, footer‐inside appears
              at  the  bottom  left  on recto (odd‐numbered) pages, and at the
              bottom right on verso (even‐numbered) pages.  The outside footer
              is the page number, except in the continuous‐rendering mode  en‐
              abled  by  the  option -rcR=1, in which case it is the topic and
              section, as in the header.  header‐middle  is  centered  in  the
              header.   If  section is an integer between 1 and 9 (inclusive),
              there is no need to specify header‐middle; an.tmac  will  supply
              text  for  it.   The macro package may also abbreviate topic and
              footer‐inside with ellipses (...)  if  they  would  overrun  the
              space  available  in  the  header and footer, respectively.  For
              HTML output, headers and footers are suppressed.

              Additionally, this macro breaks the page, resetting  the  number
              to  1  (unless  the  -rC1 option is given).  This feature is in‐
              tended only for formatting multiple man documents in sequence.

              A valid man document calls .TH once, early in the file, prior to
              any other macro calls.

              By convention, footer‐middle is the date of the most recent mod‐
              ification to the man page source document, and footer‐inside  is
              the name and version or release of the project providing it.

       .SH [heading‐text]
              Set heading‐text as a section heading.  If no argument is given,
              a  one‐line input trap is planted; text on the next line becomes
              heading‐text.  The left margin is reset to zero to set the head‐
              ing text in bold (or the font specified by the string HF),  and,
              on typesetting devices, slightly larger than the base type size.
              If  the  heading  font \*[HF] is bold, use of an italic style in
              heading‐text is mapped to the bold‐italic style if available  in
              the  font  family.   The  inset level is reset to 1, setting the
              left margin to the value of the IN register.  Text  after  head‐
              ing‐text is set as an ordinary paragraph (.P).

              The  content  of heading‐text and ordering of sections follows a
              set of common practices, as has much of the layout  of  material
              within sections.  For example, a section called “Name” or “NAME”
              must  exist,  must  be the first section after the .TH call, and
              must contain only text of the form
                     topic[, another‐topic]... \- summary‐description
              for a man page to be properly indexed.  See man(7) for the  con‐
              ventions prevailing on your system.

       .SS [subheading‐text]
              Set  subheading‐text  as a subsection heading indented between a
              section heading and an ordinary paragraph (.P).  If no  argument
              is  given,  a  one‐line  input trap is planted; text on the next
              line becomes subheading‐text.  The left margin is reset  to  the
              value of the SN register to set the heading text in bold (or the
              font specified by the string HF).  If the heading font \*[HF] is
              bold, use of an italic style in subheading‐text is mapped to the
              bold‐italic  style  if  available in the font family.  The inset
              level is reset to 1, setting the left margin to the value of the
              IN register.  Text after subheading‐text is set as  an  ordinary
              paragraph (.P).

       .EX
       .EE    Begin  and  end  example.   After .EX, filling is disabled and a
              constant‐width (monospaced) font is selected.  Calling  .EE  en‐
              ables filling and restores the previous font.

              Example  regions are useful for formatting code, shell sessions,
              and text file contents.  An example region  is  not  a  “literal
              mode” of any sort: special character escape sequences must still
              be  used to produce correct glyphs for ', -, \, ^, `, and ~, and
              sentence endings are still detected  and  additional  inter‐sen‐
              tence space applied.  If the amount of additional inter‐sentence
              spacing  is altered, the rendering of, for instance, regular ex‐
              pressions using . or ? followed by multiple spaces  can  change.
              Use the dummy character escape sequence \& before the spaces.

              These macros are extensions introduced in Ninth Edition Research
              Unix.   Systems  running  that troff, or those from Documenter’s
              Workbench, Heirloom Doctools, or Plan 9 troff support them.   To
              be  certain  your  page will be portable to systems that do not,
              copy their definitions from the an-ext.tmac file of a groff  in‐
              stallation.

       .RS [inset‐amount]
              Start a new relative inset level.  The position of the left mar‐
              gin  is  saved,  then moved right by inset‐amount, if specified,
              and by the amount of the IN register otherwise.   Calls  to  .RS
              can be nested; each increments by 1 the inset level used by .RE.
              The level prior to any .RS calls is 1.

       .RE [level]
              End  a  relative  inset.  The left margin corresponding to inset
              level level is restored.  If no argument  is  given,  the  inset
              level is reduced by 1.

   Paragraphing macros
       An  ordinary  paragraph  (.P) like this one is set without a first‐line
       indentation at the current left margin.  In man pages and other techni‐
       cal literature, definition lists are frequently encountered; these  can
       be set as “tagged paragraphs”, which have one (.TP) or more (.TQ) lead‐
       ing  tags  followed  by a paragraph that has an additional indentation.
       The indented paragraph (.IP) macro is useful to continue  the  indented
       content  of  a narrative started with .TP, or to present an itemized or
       ordered list.  All of these macros break the output line.   If  another
       paragraph  macro  has occurred since the previous .SH or .SS, they (ex‐
       cept for .TQ) follow the break with a default amount of vertical space,
       which can be changed by the deprecated .PD macro; see subsection “Hori‐
       zontal and vertical spacing” below.  They also reset the type size  and
       font style to defaults (.TQ again excepted); see subsection “Font style
       macros” below.

       .P
       .LP
       .PP    Begin  a new paragraph; these macros are synonymous.  The inden‐
              tation is reset to the default value; the left  margin,  as  af‐
              fected by .RS and .RE, is not.

       .TP [indentation]
              Set  a  paragraph  with  a leading tag, and the remainder of the
              paragraph indented.  A one‐line input trap is planted;  text  on
              the  next line, which can be formatted with a macro, becomes the
              tag, which is placed at the current left margin.  The tag can be
              extended with the \c escape sequence.  Subsequent  text  is  in‐
              dented by indentation, if specified, and by the amount of the IN
              register  otherwise.   If the tag is not as wide as the indenta‐
              tion, the paragraph starts on the same line as the tag,  at  the
              applicable  indentation,  and  continues on the following lines.
              Otherwise, the descriptive part of the paragraph begins  on  the
              line following the tag.

              The  line  containing  the tag can include a macro call, for in‐
              stance to set the tag in bold with .B.  .TP was  used  to  write
              the first paragraph of this description of .TP, and .IP the sub‐
              sequent one.

       .TQ    Set an additional tag for a paragraph tagged with .TP.  An input
              trap is planted as with .TP.

              This  macro  is  a  GNU extension not defined on systems running
              AT&T, Plan 9, or  Solaris  troff;  see  an-ext.tmac  in  section
              “Files” below.

              The  descriptions  of  .P, .LP, and .PP above were written using
              .TP and .TQ.

       .IP [tag] [indentation]
              Set an indented paragraph with an optional tag.  The tag and in‐
              dentation arguments, if present, are handled as with  .TP,  with
              the  exception  that  the  tag  argument to .IP cannot include a
              macro call.

              Two convenient uses for .IP are

                  (1) to start a new paragraph with the same indentation as an
                      immediately preceding .IP or .TP paragraph, if no inden‐
                      tation argument is given; and

                  (2) to set a paragraph with a short tag that is not semanti‐
                      cally important, such as a bullet (•)—obtained with  the
                      \(bu  special character escape sequence—or list enumera‐
                      tor, as seen in this very paragraph.

   Command synopsis macros
       .SY and .YS aid you to construct a command synopsis that has the  clas‐
       sical Unix appearance.  They break the output line.

       These  macros  are  GNU extensions not defined on systems running AT&T,
       Plan 9, or Solaris troff; see an-ext.tmac in section “Files” below.

       .SY command
              Begin synopsis.  A new paragraph begins at the left  margin  (as
              with  .P)  unless  .SY  has already been called without a corre‐
              sponding .YS, in which case only a break is performed.   Adjust‐
              ment  and automatic hyphenation are disabled.  command is set in
              bold.  If a break is required, lines after  the  first  are  in‐
              dented by the width of command plus a space.

       .YS    End  synopsis.  Indentation, adjustment, and hyphenation are re‐
              stored to their previous states.

       Multiple .SY/.YS blocks can be specified, for instance  to  distinguish
       differing  modes  of  operation  of a complex command like tar(1); each
       will be vertically separated as paragraphs are.

       .SY can be repeated before .YS to indicate synonymous ways of  invoking
       a particular mode of operation.

       groff’s  own  command‐line  interface  serves to illustrate most of the
       specimens of synopsis syntax one is likely to encounter.

              .SY groff
              .RB [ \‐abcCeEgGijklNpRsStUVXzZ ]
              .RB [ \‐d\~\c
              .IR cs ]
              .RB [ \‐d\~\c
              .IB name =\c
              .IR string ]
              .RB [ \‐D\~\c
              .IR enc ]
              (and so on similarly)
              .RI [ file\~ .\|.\|.]
              .YS
              .
              .
              .SY groff
              .B \‐h
              .
              .SY groff
              .B \‐\‐help
              .YS
              .
              .
              .SY groff
              .B \‐v
              .RI [ option\~ .\|.\|.\&]
              .RI [ file\~ .\|.\|.]
              .
              .SY groff
              .B \‐\‐version
              .RI [ option\~ .\|.\|.\&]
              .RI [ file\~ .\|.\|.]
              .YS

       produces the following output.

              groff [-abcCeEgGijklNpRsStUVXzZ] [-d cs] [-d name=string]
                    [-D enc] [-f fam] [-F dir] [-I dir] [-K enc] [-L arg]
                    [-m name] [-M dir] [-n num] [-o list] [-P arg] [-r cn]
                    [-r reg=expr] [-T dev] [-w name] [-W name] [file ...]

              groff -h
              groff --help

              groff -v [option ...] [file ...]
              groff --version [option ...] [file ...]

       Several features of the above example are of note.

       • The empty request (.), which does  nothing,  is  used  to  vertically
         space  the input file for readability by the document maintainer.  Do
         not put blank (empty) lines in a man page source document.

       • Command and option names are presented in bold to cue the  user  that
         they should be input literally.

       • Option  dashes  are specified with the \- escape sequence; this is an
         important practice to make them clearly  visible  and  to  facilitate
         copy‐and‐paste  from  the rendered man page to a shell prompt or text
         file.

       • Option arguments and command operands are presented in  italics  (but
         see  subsection “Font style macros” below regarding terminals) to cue
         the user that they must be replaced with appropriate text.

       • Symbols that are neither to be typed literally nor  replaced  at  the
         user’s  discretion  appear  in the roman style; brackets surround op‐
         tional arguments, and an ellipsis indicates that the previous syntac‐
         tical element may be repeated arbitrarily.

       • The non‐breaking adjustable space escape sequence \~ is used to  pre‐
         vent  the  output  line from being broken within the option brackets;
         see subsection “Portability” below.

       • The output line continuation escape sequence \c  is  used  with  font
         style  alternation  macros  to  allow all three font styles to be set
         without (breakable) space among them;  see  subsection  “Portability”
         below.

       • The dummy character escape sequence \& follows the ellipsis when fur‐
         ther  text  will  follow  after space on the output line, keeping its
         last period from being interpreted as the end of a sentence and caus‐
         ing additional inter‐sentence space to be placed after it.  See  sub‐
         section “Portability” below.

   Hyperlink macros
       Man page cross references like ls(1) are best presented with .MR.  Text
       may  be  hyperlinked to email addresses with .MT/.ME or other URIs with
       .UR/.UE.  Hyperlinked text is supported on HTML and terminal output de‐
       vices; terminals and pager programs must support ECMA‐48 OSC  8  escape
       sequences  (see grotty(1)).  When device support is unavailable or dis‐
       abled with the U register (see section “Options” below),  .MT  and  .UR
       URIs are rendered between angle brackets after the linked text.

       .MT,  .ME,  .UR, and .UE are GNU extensions not defined on systems run‐
       ning AT&T, Plan 9, or Solaris troff; see an-ext.tmac in section “Files”
       below.  Plan 9 from User Space’s troff implements .MR.

       The arguments to .MR, .MT, and .UR should be prepared  for  typesetting
       since  they can appear in the output.  Use special character escape se‐
       quences to encode Unicode basic Latin characters where necessary,  par‐
       ticularly  the  hyphen‐minus.  (See section “Portability” below.)  URIs
       can be lengthy; rendering them can  result  in  jarring  adjustment  or
       variations in line length, or troff warnings when a hyperlink is longer
       than  an  output line.  The application of non‐printing break point es‐
       cape sequences \: after each slash (or series thereof), and before each
       dot (or series thereof) is recommended as a rule of thumb.  The  former
       practice  avoids forcing a trailing slash in a URI onto a separate out‐
       put line, and the latter helps the reader to  avoid  mistakenly  inter‐
       preting  a dot at the end of a line as a period (or multiple dots as an
       ellipsis).  Thus,
              .UR http://\:example\:.com/\:fb8afcfbaebc74e\:.cc
       has several potential break points in the URI shown.   Consider  adding
       break  points before or after at signs in email addresses, and question
       marks, ampersands, and number signs in HTTP(S) URIs.  The formatter re‐
       moves \: escape sequences from hyperlinks when supplying device control
       commands to output drivers.

       .MR topic manual‐section [trailing‐text]
              (since groff 1.23) Set a man page cross reference as “topic(man‐
              ual‐section)”.   If  trailing‐text  (typically  punctuation)  is
              specified,  it follows the closing parenthesis without interven‐
              ing space.  Hyphenation is disabled while the cross reference is
              set.  topic is set in the font specified by the MF string.   The
              cross  reference hyperlinks to a URI of the form “man:topic(man‐
              ual‐section)”.

                     The output driver
                     .MR grops 1
                     produces PostScript from
                     .I troff
                     output.
                     .
                     The Ghostscript program (\c
                     .MR gs 1 )
                     interprets PostScript and PDF.

       .MT address
       .ME [trailing‐text]
              Identify address as an RFC 6068 addr‐spec for  a  “mailto:”  URI
              with  the text between the two macro calls as the link text.  An
              argument to .ME is placed after the link text without  interven‐
              ing  space.  address may not be visible in the rendered document
              if hyperlinks are enabled and supported by  the  output  driver.
              If they are not, address is set in angle brackets after the link
              text  and  before trailing‐text.  If hyperlinking is enabled but
              there is no link text,  address  is  formatted  and  hyperlinked
              without angle brackets.

              When rendered by groff to a PostScript device,

                     Contact
                     .MT fred\:.foonly@\:fubar\:.net
                     Fred Foonly
                     .ME
                     for more information.

              displays  as  “Contact  Fred  Foonly ⟨fred.foonly@fubar.net⟩ for
              more information.”.

       .UR uri
       .UE [trailing‐text]
              Identify uri as an RFC 3986 URI hyperlink with the text  between
              the  two  macro  calls  as the link text.  An argument to .UE is
              placed after the link text without intervening space.   uri  may
              not  be  visible  in the rendered document if hyperlinks are en‐
              abled and supported by the output driver.  If they are not,  uri
              is  set  in angle brackets after the link text and before trail‐
              ing‐text.  If hyperlinking is enabled but there is no link text,
              uri is formatted and hyperlinked without angle brackets.

              When rendered by groff to a PostScript device,

                     The GNU Project of the Free Software Foundation
                     hosts the
                     .UR https://\:www\:.gnu\:.org/\:software/\:groff/
                     .I groff
                     home page
                     .UE .

              displays as “The GNU Project of  the  Free  Software  Foundation
              hosts   the   groff   home  page  ⟨https://www.gnu.org/software/
              groff/⟩.”.

       The hyperlinking of .TP paragraph tags with .UR/.UE and .MT/.ME is  not
       yet  supported;  if attempted, the hyperlink will be typeset at the be‐
       ginning of the indented paragraph even on hyperlink‐supporting devices.

   Font style macros
       The man macro package is limited in its font styling options,  offering
       only bold (.B), italic (.I), and roman.  Italic text is usually set un‐
       derscored instead on terminal devices.  The .SM and .SB macros set text
       in  roman  or  bold, respectively, at a smaller type size; these differ
       visually from regular‐sized roman or bold text only on typesetting  de‐
       vices.   It  is often necessary to set text in different styles without
       intervening space.  The macros .BI, .BR, .IB, .IR, .RB, and .RI,  where
       “B”,  “I”,  and “R” indicate bold, italic, and roman, respectively, set
       their odd‐ and even‐numbered arguments in alternating styles,  with  no
       space separating them.

       Because  font styles are presentational rather than semantic, conflict‐
       ing traditions have arisen regarding which font styles should  be  used
       to  mark  file or path names, environment variables, and inlined liter‐
       als.

       The default type size and family for typesetting  devices  is  10‐point
       Times,  except on the X75-12 and X100-12 devices where the type size is
       12 points.  The default style is roman.

       .B [text]
              Set text in bold.  If no argument is  given,  a  one‐line  input
              trap  is  planted;  text  on the next line, which can be further
              formatted with a macro, is set in bold.

              Use bold for literal portions of syntax synopses,  for  command‐
              line  options  in  running text, and for literals that are major
              topics of the subject under discussion; for example,  this  page
              uses  bold for macro, string, and register names.  In an .EX/.EE
              example of interactive I/O (such as a shell session),  set  only
              user input in bold.

       .I [text]
              Set text in an italic or oblique face.  If no argument is given,
              a  one‐line  input trap is planted; text on the next line, which
              can be further formatted with a macro, is set in  an  italic  or
              oblique face.

              Use  italics for file and path names, for environment variables,
              for C data types, for enumeration or preprocessor  constants  in
              C,  for  variant (user‐replaceable) portions of syntax synopses,
              for the first occurrence (only) of a technical concept being in‐
              troduced, for names of journals and  of  literary  works  longer
              than  an article, and anywhere a parameter requiring replacement
              by the user is encountered.  An exception involves variant  text
              in  a  context  already typeset in italics, such as file or path
              names with replaceable components; in  such  cases,  follow  the
              convention of mathematical typography: set the file or path name
              in  italics as usual but use roman for the variant part (see .IR
              and .RI below), and italics again in running roman text when re‐
              ferring to the variant material.

       .SM [text]
              Set text one point smaller than the default type size  on  type‐
              setting devices.  If no argument is given, a one‐line input trap
              is  planted; text on the next line, which can be further format‐
              ted with a macro, is set smaller.

              Note: terminals will render text at normal size instead.  Do not
              rely upon .SM to communicate semantic information distinct  from
              using roman style at normal size; it will be hidden from readers
              using such devices.

       .SB [text]
              Set  text in bold and (on typesetting devices) one point smaller
              than the default type size.  If no argument is given, a one‐line
              input trap is planted; text on the next line, which can be  fur‐
              ther  formatted  with a macro, is set smaller and in bold.  This
              macro is an extension introduced in SunOS 4.0.

              Note: terminals will render text in bold at the normal size  in‐
              stead.  Do not rely upon .SB to communicate semantic information
              distinct from using bold style at normal size; it will be hidden
              from readers using such devices.

       Observe  what  is  not prescribed for setting in bold or italics above:
       elements of “synopsis language” such as ellipses  and  brackets  around
       options; proper names and adjectives; titles of anything other than ma‐
       jor works of literature; identifiers for standards documents or techni‐
       cal  reports such as CSTR #54, RFC 1918, Unicode 13.0, or POSIX.1‐2017;
       acronyms; and occurrences after the first of a technical term.

       Be frugal with italics for emphasis, and particularly with bold.  Arti‐
       cle titles and brief runs of literal text, such as references to  indi‐
       vidual  characters  or  short strings, including section and subsection
       headings of man pages, are suitable  objects  for  quotation;  see  the
       \(lq, \(rq, \(oq, and \(cq escape sequences in subsection “Portability”
       below.

       Unlike  the  above font style macros, the font style alternation macros
       below set no input traps; they must be given arguments to have  effect.
       Italic  corrections are applied as appropriate.  If a space is required
       within an argument, first consider whether the  same  result  could  be
       achieved  with as much clarity by using single‐style macros on separate
       input lines.  When it cannot, double‐quote an argument  containing  em‐
       bedded  space  characters.  Setting all three different styles within a
       word presents challenges; it is possible with the \c and/or  \f  escape
       sequences.  See subsection “Portability” below for approaches.

       .BI bold‐text italic‐text ...
              Set each argument in bold and italics, alternately.

                     .BI -r  register = numeric‐expression

       .BR bold‐text roman‐text ...
              Set each argument in bold and roman, alternately.

                     After
                     .B .NH
                     is called,

       .IB italic‐text bold‐text ...
              Set each argument in italics and bold, alternately.

                     In places where
                     .IB n th
                     is allowed,

       .IR italic‐text roman‐text ...
              Set each argument in italics and roman, alternately.

                     Use GNU
                     .IR pic 's
                     .B figname
                     command to change the name of the vbox.

       .RB roman‐text bold‐text ...
              Set each argument in roman and bold, alternately.

                     if
                     .I file
                     is
                     .RB \[lq] \- \[rq],
                     the standard input stream is read.

       .RI roman‐text italic‐text ...
              Set each argument in roman and italics, alternately.

                     .RI ( tpic
                     was a fork of AT&T
                     .I pic
                     by Tim Morgan of the University of California at Irvine

   Horizontal and vertical spacing
       The  indentation  argument accepted by .IP, .TP, and the deprecated .HP
       is a number plus an optional scaling unit, as  is  .RS’s  inset‐amount.
       If  no scaling unit is given, the man package assumes “n”; that is, the
       width of a letter “n” in the font current when the macro is called (see
       section “Measurements” in groff(7)).  An  indentation  specified  in  a
       call  to  .IP, .TP, or the deprecated .HP persists until (1) another of
       these macros is called with an indentation argument, or (2)  .SH,  .SS,
       or .P or its synonyms is called; these clear the indentation entirely.

       The  left  margin used by ordinary paragraphs set with .P (and its syn‐
       onyms) not within an .RS/.RE relative inset is 7.2n for typesetting de‐
       vices and 7n for terminal devices (but see the -rIN option).   Headers,
       footers  (both set with .TH), and section headings (.SH) are set at the
       page offset (see groff(7)) and subsection headings (.SS) indented  from
       it by 3n (but see the -rSN option).

       It  may  be  helpful to think of the left margin and indentation as re‐
       lated but distinct concepts; groff’s implementation of  the  man  macro
       package  tracks them separately.  The left margin is manipulated by .RS
       and .RE (and by .SH and .SS, which reset it to the default).   Indenta‐
       tion  is  controlled by the paragraphing macros (though, again, .SH and
       .SS reset it); it is imposed  by  the  .TP,  .IP,  and  deprecated  .HP
       macros,  and  cancelled  by  .P and its synonyms.  An extensive example
       follows.

       This ordinary (.P) paragraph is not in a relative  inset  nor  does  it
       possess an indentation.

              Now  we have created a relative inset (in other words, moved the
              left margin) with .RS and  started  another  ordinary  paragraph
              with .P.

              tag    This  tagged paragraph, set with .TP, is still within the
                     .RS region, but lines after the first have  a  supplemen‐
                     tary indentation that the tag lacks.

                     A  paragraph  like this one, set with .IP, will appear to
                     the reader as also associated with the tag above, because
                     .IP re‐uses the previous paragraph’s  indentation  unless
                     given  an  argument  to change it.  This paragraph is af‐
                     fected both by the moved left margin (.RS)  and  indenta‐
                     tion (.IP).
                     ┌──────────────────────────────────┐
                     │ This table is affected both by   │
                     │ the left margin and indentation. │
                     └──────────────────────────────────┘

              •      This indented paragraph has a bullet for a tag, making it
                     more  obvious  that  the  left margin and indentation are
                     distinct; only the former affects the tag, but  both  af‐
                     fect the text of the paragraph.

              This  ordinary  (.P)  paragraph  resets the indentation, but the
              left margin is still inset.
              ┌─────────────────────────────┐
              │ This table is affected only │
              │ by the left margin.         │
              └─────────────────────────────┘

       Finally, we have ended the relative inset by using .RE, which  (because
       we  used  only  one  .RS/.RE pair) has reset the left margin to the de‐
       fault.  This is an ordinary .P paragraph.

       Resist the temptation to mock up tabular or  multi‐column  output  with
       tab  characters  or  the indentation arguments to .IP, .TP, .RS, or the
       deprecated .HP; the result may not render comprehensibly on  an  output
       device you fail to check, or which is developed in the future.  The ta‐
       ble preprocessor tbl(1) can likely meet your needs.

       Several  macros  insert vertical space: .SH, .SS, .TP, .P (and its syn‐
       onyms), .IP, and the deprecated .HP.  The default inter‐section and in‐
       ter‐paragraph spacing is is 1v for terminal devices and 0.4v for  type‐
       setting  devices  (“v”  is a unit of vertical distance, where 1v is the
       distance between adjacent text baselines in a single‐spaced  document).
       (The deprecated macro .PD can change this vertical spacing, but its use
       is  discouraged.)  Between .EX and .EE calls, the inter‐paragraph spac‐
       ing is 1v regardless of output device.

   Registers
       Registers are described in section “Options” below.  They  can  be  set
       not  only  on  the command line but in the site man.local file as well;
       see section “Files” below.

   Strings
       The following strings are defined for use in  man  pages.   Others  are
       supported  for  configuration of rendering parameters; see section “Op‐
       tions” below.

       \*R    interpolates a special character escape sequence for the “regis‐
              tered sign” glyph, \(rg, if available, and “(Reg.)” otherwise.

       \*S    interpolates an escape sequence setting the  type  size  to  the
              document default.

       \*(lq
       \*(rq  interpolate  special  character  escape  sequences  for left and
              right double‐quotation marks, \(lq and \(rq, respectively.

       \*(Tm  interpolates a special character escape sequence for the  “trade
              mark sign” glyph, \(tm, if available, and “(TM)” otherwise.

       None  of the above is necessary in a contemporary man page.  \*S is su‐
       perfluous, since type size changes are invisible  on  terminal  devices
       and macros that change it restore its original value afterward.  Better
       alternatives  exist  for the rest; simply use the \(rg, \(lq, \(rq, and
       \(tm special character escape sequences directly.  Unless  a  man  page
       author  is  aiming for a pathological level of portability, such as the
       composition of pages for consumption on simulators of 1980s  Unix  sys‐
       tems  (or  Solaris  troff,  though  even  it  supports \(rg), the above
       strings should be avoided.

   Portability
       It is wise to quote multi‐word section and subsection headings; the .SH
       and .SS macros of man(7) implementations descended from Seventh Edition
       Unix supported six arguments at most.  A similar restriction applied to
       the .B, .I, .SM, and font style alternation macros.

       The two major syntactical categories for formatting control in the roff
       language are requests and escape sequences.  Since the man  macros  are
       implemented  in  terms of groff requests and escape sequences, one can,
       in principle, supplement the functionality of  man  with  these  lower‐
       level elements where necessary.

       However, using raw groff requests (apart from the empty request “.”) is
       likely  to  make your page render poorly when processed by other tools;
       many of these attempt to interpret page sources directly for conversion
       to HTML.  Some requests make implicit  assumptions  about  things  like
       character  and  page  sizes  that  may not hold in an HTML environment;
       also, many of these viewers don’t interpret the full groff  vocabulary,
       a  problem that can lead to portions of your text being omitted or pre‐
       sented incomprehensibly.

       For portability to modern viewers, it is best to write your page solely
       with the macros described in this page (except for the ones  identified
       as  deprecated, which should be avoided).  The macros we have described
       as extensions (.EX/.EE, .SY/.YS, .TQ, .UR/.UE, .MT/.ME, .MR,  and  .SB)
       should be used with caution, as they may not be built in to some viewer
       that is important to your audience.  See an-ext.tmac in section “Files”
       below.

       Similar  caveats  apply to escape sequences.  Some escape sequences are
       however required for correct typesetting even in man pages and  usually
       do not cause portability problems.  Several of these render glyphs cor‐
       responding  to punctuation code points in the Unicode basic Latin range
       (U+0000–U+007F) that are handled specially in roff  input;  the  escape
       sequences below must be used to render them correctly and portably when
       documenting  material  that  uses them syntactically—namely, any of the
       set ' - \ ^ ` ~ (apostrophe, dash or minus, backslash, caret, grave ac‐
       cent, tilde).

       \"     Comment.  Everything after the double‐quote to the  end  of  the
              input line is ignored.  Whole‐line comments should be placed im‐
              mediately after the empty request (“.”).

       \newline
              Join the next input line to the current one.  Except for the up‐
              date of the input line counter (used for diagnostic messages and
              related purposes), a series of lines ending in backslash‐newline
              appears  to  groff  as a single input line.  Use this escape se‐
              quence to split excessively long input lines for document  main‐
              tenance.

       \%     Control  hyphenation.   The  location  of  this  escape sequence
              within a word marks a hyphenation point,  supplementing  groff’s
              automatic  hyphenation patterns.  At the beginning of a word, it
              suppresses any hyphenation breaks within except those  specified
              with \%.

       \:     Insert  a  non‐printing break point.  A word can break at such a
              point, but a hyphen glyph is not written to  the  output  if  it
              does.   This  escape  sequence is an input word boundary, so the
              remainder of the word is subject to hyphenation as normal.   You
              can  use  \: and \% in combination to control breaking of a file
              name or URI or to permit hyphenation only after certain explicit
              hyphens within a word.  See subsection “Hyperlink macros”  above
              for an example.

              This  escape  sequence  is  a  groff extension also supported by
              Heirloom Doctools troff 050915 (September 2005),  mandoc  1.14.5
              (2019‐03‐10),  and  neatroff  (commit 399a4936, 2014‐02‐17), but
              not by Plan 9, Solaris, or Documenter’s Workbench troffs.

       \~     Adjustable non‐breaking space.  Use this escape sequence to pre‐
              vent a break inside a short phrase or between a numerical  quan‐
              tity and its corresponding unit(s).

                     Before starting the motor,
                     set the output speed to\~1.
                     There are 1,024\~bytes in 1\~KiB.
                     CSTR\~#8 documents the B\~language.

              This  escape  sequence  is  a  groff extension also supported by
              Heirloom Doctools troff 050915 (September  2005),  mandoc  1.9.5
              (2009‐09‐21),   neatroff  (commit  1c6ab0f6e,  2016‐09‐13),  and
              Plan 9 from User Space troff  (commit  93f8143600,  2022‐08‐12),
              but not by Solaris or Documenter’s Workbench troffs.

       \&     Dummy  character.   Insert  at the beginning of an input line to
              prevent a dot or apostrophe from being interpreted as  beginning
              a  roff  control line.  Append to an end‐of‐sentence punctuation
              sequence to keep it from being recognized as such.

       \|     Thin space (one‐sixth em on typesetters,  zero‐width  on  termi‐
              nals);   a  non‐breaking  space.   Used  primarily  in  ellipses
              (“.\|.\|.”)  to space the dots more  pleasantly  on  typesetting
              devices like dvi, pdf, and ps.

       \c     End  a  text line without inserting space or attempting a break.
              Normally, if filling is enabled, the  end  of  a  text  line  is
              treated  like  a  space;  an output line may be broken there (if
              not, an adjustable space is inserted); if filling  is  disabled,
              the line will be broken there, as in .EX/.EE examples.  The next
              line  is interpreted as usual and can include a macro call (con‐
              trast with \newline).  \c is useful when three font  styles  are
              needed in a single word, as in a command synopsis.

                     .RB [ \-\-stylesheet=\c
                     .IR name ]

              It  also  helps  when  changing font styles in .EX/.EE examples,
              since they are not filled.

                     .EX
                     $ \c
                     .B groff \-T utf8 \-Z \c
                     .I file \c
                     .B | grotty \-i
                     .EE

              Alternatively, and perhaps with better portability, the \f  font
              selection  escape  sequence can be used; see below.  Using \c to
              continue a .TP paragraph tag across multiple  input  lines  will
              render  incorrectly with groff 1.22.3, mandoc 1.14.1, older ver‐
              sions of these programs, and perhaps with some other formatters.

       \e     Format the current escape character on the output;  widely  used
              in  man pages to render a backslash glyph.  It works reliably as
              long as the “.ec” request is not used, which should never happen
              in man pages, and it is slightly more portable than the more ex‐
              plicit \(rs (“reverse solidus”)  special  character  escape  se‐
              quence.

       \fB, \fI, \fR, \fP
              Switch  to  bold,  italic, roman, or back to the previous style,
              respectively.  Either \f or \c is needed  when  three  different
              font styles are required in a word.

                     .RB [ \-\-reference\-dictionary=\fI\,name\/\fP ]

                     .RB [ \-\-reference\-dictionary=\c
                     .IR name ]

              Style  escape  sequences may be more portable than \c.  As shown
              above, it is up to you to account for  italic  corrections  with
              “\/”  and  “\,”, which are themselves GNU extensions, if desired
              and if supported by your implementation.

              \fP reliably returns to the style in use  immediately  preceding
              the  previous  \f  escape  sequence only if no sectioning, para‐
              graph, or style macro calls have intervened.

              As long as at most two styles are needed in a word, style macros
              like .B and .BI usually result in more readable roff source than
              \f escape sequences do.

       Several special characters are also widely portable.   Except  for  \-,
       \(em,  and  \(ga, AT&T troff did not consistently define the characters
       listed below, but its descendants, like Plan 9 or Solaris troff, can be
       made to support them by defining them in font description files, making
       them aliases of existing glyphs if necessary; see groff_font(5).

       \-     Minus sign or basic Latin hyphen‐minus.   This  escape  sequence
              produces  the  Unix command‐line option dash in the output.  “-”
              is a hyphen in the roff language; some output devices replace it
              with U+2010 (hyphen) or similar.

       \(aq   Basic Latin neutral apostrophe.  Some output devices format  “'”
              as a right single quotation mark.

       \(oq
       \(cq   Opening  (left) and closing (right) single quotation marks.  Use
              these for paired directional single quotes, ‘like this’.

       \(dq   Basic Latin quotation mark (double quote).  Use in  macro  calls
              to  prevent ‘"” from being interpreted as beginning a quoted ar‐
              gument, or simply for readability.

                     .TP
                     .BI "split \(dq" text \(dq

       \(lq
       \(rq   Left and right double quotation marks.  Use these for paired di‐
              rectional double quotes, “like this”.

       \(em   Em‐dash.  Use for an interruption—such as  this  one—in  a  sen‐
              tence.

       \(en   En‐dash.   Use to separate the ends of a range, particularly be‐
              tween numbers; for example, “the digits 1–9”.

       \(ga   Basic Latin grave accent.  Some output devices format “`”  as  a
              left single quotation mark.

       \(ha   Basic Latin circumflex accent (“hat”).  Some output devices for‐
              mat  “^”  as U+02C6 (modifier letter circumflex accent) or simi‐
              lar.

       \(rs   Reverse solidus (backslash).  The backslash is the  default  es‐
              cape  character  in  the roff language, so it does not represent
              itself in output.  Also see \e above.

       \(ti   Basic Latin tilde.  Some output devices  format  “~”  as  U+02DC
              (small tilde) or similar.

       For  maximum  portability,  escape sequences and special characters not
       listed above are better avoided in man pages.

   Hooks
       Two macros, both GNU extensions, are called internally by the groff man
       package to format page headers and footers and can be redefined by  the
       administrator  in  a site’s man.local file (see section “Files” below).
       The presentation of .TH above describes the default headers  and  foot‐
       ers.  Because these macros are hooks for groff man internals, man pages
       have no reason to call them.  Such hook definitions will likely consist
       of  “.sp”  and “.tl” requests.  They must also increase the page length
       with “.pl” requests in continuous rendering mode; .PT  furthermore  has
       the  responsibility  of emitting a PDF bookmark after writing the first
       page header in a document.  Consult  the  existing  implementations  in
       an.tmac when drafting replacements.

       .BT    Set the page footer text (“bottom trap”).

       .PT    Set the page header text (“page trap”).

       To  remove  a  page  header  or footer entirely, define the appropriate
       macro as empty rather than deleting it.

   Deprecated features
       Use of the following in man pages for public distribution  is  discour‐
       aged.

       .AT [system [release]]
              Alter  the footer for use with legacy AT&T man pages, overriding
              any definition of the footer‐inside argument to .TH.  This macro
              exists only to render man pages from historical systems.

              system can be any of the following.

                     3      7th edition (default)

                     4      System III

                     5      System V

              The optional release argument specifies the release  number,  as
              in “System V Release 3”.

       .DT    Reset tab stops to the default (every 0.5i [inches]).

              Use  of  this  presentation‐oriented  macro  is  deprecated.  It
              translates poorly to HTML, under which exact space  control  and
              tabulation are not readily available.  Thus, information or dis‐
              tinctions  that  you  use  tab stops to express are likely to be
              lost.  If you feel tempted to change the  tab  stops  such  that
              calling  this  macro  later  is  desirable  to restore them, you
              should probably be composing a table using tbl(1) instead.

       .HP [indentation]
              Set up a paragraph with a hanging left indentation.  The  inden‐
              tation argument, if present, is handled as with .TP.

              Use  of this presentation‐oriented macro is deprecated.  A hang‐
              ing indentation cannot be expressed naturally  under  HTML,  and
              non‐roff‐based  man  page interpreters may treat .HP as an ordi‐
              nary paragraph.  Thus, information or distinctions you  mean  to
              express with indentation may be lost.

       .OP option‐name [option‐argument]
              Indicate an optional command parameter called option‐name, which
              is  set  in  bold.  If the option takes an argument, specify op‐
              tion‐argument using a noun,  abbreviation,  or  hyphenated  noun
              phrase.   If present, option‐argument is preceded by a space and
              set in italics.  Square brackets in roman  surround  both  argu‐
              ments.

              Use  of  this  quasi‐semantic macro, an extension originating in
              Documenter’s Workbench troff, is deprecated.  It  cannot  easily
              be  used to annotate options that take optional arguments or op‐
              tions whose arguments have internal structure (such as a mixture
              of literal and variable  components).   One  could  work  around
              these  limitations  with font selection escape sequences, but it
              is preferable to use font style alternation macros, which afford
              greater flexibility.

       .PD [vertical‐space]
              Define the vertical space between paragraphs  or  (sub)sections.
              The  optional  argument vertical‐space specifies the amount; the
              default scaling unit is “v”.  Without an argument,  the  spacing
              is  reset  to  its default value; see subsection “Horizontal and
              vertical spacing” above.

              Use of  this  presentation‐oriented  macro  is  deprecated.   It
              translates  poorly  to HTML, under which exact control of inter‐
              paragraph spacing is not readily available.   Thus,  information
              or  distinctions  that  you  use .PD to express are likely to be
              lost.

       .UC [version]
              Alter the footer for use with legacy BSD man  pages,  overriding
              any definition of the footer‐inside argument to .TH.  This macro
              exists only to render man pages from historical systems.

              version can be any of the following.

                     3      3rd Berkeley Distribution (default)

                     4      4th Berkeley Distribution

                     5      4.2 Berkeley Distribution

                     6      4.3 Berkeley Distribution

                     7      4.4 Berkeley Distribution

   History
       M.  Douglas  McIlroy ⟨m.douglas.mcilroy@dartmouth.edu⟩ designed, imple‐
       mented, and documented the AT&T man macros for Unix  Version  7  (1979)
       and  employed them to edit the first volume of its Programmer’s Manual,
       a compilation of all man pages supplied by the system.  That  man  sup‐
       ported  the macros listed in this page not described as extensions, ex‐
       cept .P and the deprecated .AT and .UC.  The only strings defined  were
       R and S; no registers were documented.

       .UC  appeared in 3BSD (1980).  Unix System III (1980) introduced .P and
       exposed the registers IN and LL, which had  been  internal  to  Seventh
       Edition  Unix  man.   PWB/UNIX  2.0  (1980)  added the Tm string.  4BSD
       (1980) added lq and rq strings.  SunOS 2.0 (1985) recognized C,  D,  P,
       and  X  registers.   4.3BSD (1986) added .AT and .P.  Ninth Edition Re‐
       search Unix (1986) introduced .EX and .EE.  SunOS 4.0 (1988) added .SB.

       The foregoing features were what James Clark implemented in early  ver‐
       sions  of  groff.   Later,  groff  1.20 (2009) originated .SY/.YS, .TQ,
       .MT/.ME, and .UR/.UE.  Plan 9 from User Space’s troff introduced .MR in
       2020.

Options
       The following groff options set registers (with -r) and  strings  (with
       -d)  recognized and used by the man macro package.  To ensure rendering
       consistent with output device capabilities and reader preferences,  man
       pages should never manipulate them.

       -dAD=adjustment‐mode
              Set  line  adjustment to adjustment‐mode, which is typically “b”
              for adjustment to both margins (the default), or  “l”  for  left
              alignment  (ragged right margin).  Any valid argument to groff’s
              “.ad”  request  may  be  used.   See  groff(7)  for  less‐common
              choices.

       -rcR=1 Enable  continuous rendering.  Output is not paginated; instead,
              one (potentially very long) page is produced.  This is  the  de‐
              fault  for  terminal and HTML devices.  Use -rcR=0 to disable it
              on terminal devices; on HTML devices, it cannot be disabled.

       -rC1   Number output pages consecutively, in  strictly  increasing  se‐
              quence, rather than resetting the page number to 1 (or the value
              of register P) with each new man document.

       -rCS=1 Set  section headings (the argument(s) to .SH) in full capitals.
              This transformation is off by default because it  discards  case
              distinction information.

       -rCT=1 Set the man page topic (the first argument to .TH) in full capi‐
              tals  in headers and footers.  This transformation is off by de‐
              fault because it discards case distinction information.

       -rD1   Enable double‐sided layout, formatting footers for even and  odd
              pages  differently;  see  the  description  of .TH in subsection
              “Document structure macros” above.

       -rFT=footer‐distance
              Set distance of the footer relative to the bottom of the page to
              footer‐distance; this amount is always negative.  At  one  half‐
              inch above this location, the page text is broken before writing
              the  footer.   Ignored  if continuous rendering is enabled.  The
              default is -0.5i.

       -dHF=heading‐font
              Set the font used for section and subsection headings;  the  de‐
              fault  is “B” (bold style of the default family).  Any valid ar‐
              gument to groff’s “.ft” request may be used.  See groff(7).

       -rHY=0 Disable automatic hyphenation.  Normally,  it  is  enabled  (1).
              The hyphenation mode is determined by the groff locale; see sec‐
              tion “Localization“ of groff(7).

       -rIN=standard‐indentation
              Set  the  amount of indentation used for ordinary paragraphs (.P
              and its synonyms) and the default  indentation  amount  used  by
              .IP, .RS, .TP, and the deprecated .HP.  See subsection “Horizon‐
              tal  and  vertical spacing” above for the default.  For terminal
              devices, standard‐indentation should always be an integer multi‐
              ple of unit “n” to get consistent indentation.

       -rLL=line‐length
              Set line length; the default is 78n  for  terminal  devices  and
              6.5i for typesetting devices.

       -rLT=title‐length
              Set  the line length for titles.  (“Titles” is the roff term for
              headers and footers.)  By default, it is set to the line  length
              (see -rLL above).

       -dMF=man‐page‐topic‐font
              Set  the  font  used  for  man  page topics named in .TH and .MR
              calls; the default is “I” (italic style of the default  family).
              Any valid argument to groff’s “.ft” request may be used.  If the
              MF  string ends in “I”, it is assumed to be an oblique typeface,
              and italic corrections are applied before  and  after  man  page
              topics.

       -rPn   Start enumeration of pages at n.  The default is 1.

       -rStype‐size
              Use  type‐size  for  the document’s body text; acceptable values
              are 10, 11, or 12 points.  See subsection  “Font  style  macros”
              above for the default.

       -rSN=subsection‐indentation
              Set  indentation  of  subsection headings to subsection‐indenta‐
              tion.  See subsection “Horizontal and  vertical  spacing”  above
              for the default.

       -rU1   Enable  generation  of  URI hyperlinks in the grohtml and grotty
              output drivers.  grohtml enables them by  default;  grotty  does
              not,  pending more widespread pager support for OSC 8 escape se‐
              quences.  Use -rU0 to disable hyperlinks; this will make the ar‐
              guments to MT and UR calls visible in the document text produced
              by link‐capable drivers.

       -rXp   Number successors of page p as pa, pb, pc, and  so  forth.   The
              register  tracking the suffixed page letter uses format “a” (see
              the “.af” request in groff(7)).  For example,  the  option  -rX2
              produces  the  following  page  numbers: 1, 2, 2a, 2b, ..., 2aa,
              2ab, and so on.

Files
       /usr/share/groff/1.23.0/tmac/an.tmac
              Most man macros are defined in this file.  It also loads  exten‐
              sions from an-ext.tmac (see below).

       /usr/share/groff/1.23.0/tmac/andoc.tmac
              This  brief  groff program detects whether the man or mdoc macro
              package is being used by a document and loads the correct  macro
              definitions,  taking advantage of the fact that pages using them
              must call .TH or .Dd, respectively, before any other macros.   A
              man program or user typing, for example, “groff -mandoc page.1”,
              need  not know which package the file page.1 uses.  Multiple man
              pages, in either format, can  be  handled;  andoc  reloads  each
              macro package as necessary.

       /usr/share/groff/1.23.0/tmac/an-ext.tmac
              Except  for .SB, definitions of macros described above as exten‐
              sions are contained in this file; in some cases, they  are  sim‐
              pler  versions  of definitions appearing in an.tmac, and are ig‐
              nored if the formatter is GNU troff.  They  are  written  to  be
              compatible  with  AT&T troff and permissively licensed—not copy‐
              lefted.  To reduce the risk of name space collisions, string and
              register names begin only with “m”.  We encourage man  page  au‐
              thors who are concerned about portability to legacy Unix systems
              to  copy  these definitions into their pages, and maintainers of
              troff implementations or  work‐alike  systems  that  format  man
              pages to re‐use them.

              The  definitions  for  these  macros are read after a page calls
              .TH, so they will replace any macros of the same names preceding
              it in your file.  If you use your own implementations  of  these
              macros, they must be defined after .TH is called to have any ef‐
              fect.   Furthermore, it is wise to define such page‐local macros
              (if at all) after the “Name” section to accommodate timid  make‐
              whatis  or mandb implementations that may give up their scan for
              indexing material early.

       /usr/share/groff/1.23.0/tmac/man.tmac
              This is a wrapper that loads an.tmac.

       /usr/share/groff/1.23.0/tmac/mandoc.tmac
              This is a wrapper that loads andoc.tmac.

       /usr/share/groff/site-tmac/man.local
              Put site‐local changes and customizations into this file.

                     .\" Use narrower indentation on terminals and similar.
                     .if n .nr IN 4n
                     .\" Put only one space after the end of a sentence.
                     .ss 12 0 \" See groff(7).
                     .\" Keep pages narrow even on wide terminals.
                     .if n .if \n[LL]>78n .nr LL 78n
                     .\" Ensure hyperlinks are enabled for terminals.
                     .nr U 1

              On multi‐user systems, it is more  considerate  to  users  whose
              preferences  may  differ from the administrator’s to be less ag‐
              gressive with such settings, or to permit their override with  a
              user‐specific  man.local  file.  Place the requests below at the
              end of the site‐local file to manifest courtesy.
                     .soquiet \V[XDG_CONFIG_HOME]/man.local
                     .soquiet \V[HOME]/.man.local
              However, a security‐sandboxed man(1) program may lack permission
              to open such files.

Notes
       Some tips on troubleshooting your man pages follow.

       • Some ASCII characters look funny or copy and paste wrong.
              On devices with large glyph repertoires, like UTF‐8‐capable ter‐
              minals and PDF, several  keyboard  glyphs  are  mapped  to  code
              points  outside  the Unicode basic Latin range because that usu‐
              ally results in better typography in  the  general  case.   When
              documenting  GNU/Linux  command  or  C language syntax, however,
              this translation is sometimes not desirable.

              To get a “literal”...   ...should be input.
              ────────────────────────────────────────────
                                  '   \(aq
                                  -   \-
                                  \   \(rs
                                  ^   \(ha
                                  `   \(ga
                                  ~   \(ti
              ────────────────────────────────────────────

              Additionally, if a neutral double quote (") is needed in a macro
              argument, you can use \(dq to get it.  You should not  use  \(aq
              for an ordinary apostrophe (as in “can’t”) or \- for an ordinary
              hyphen  (as in “word‐aligned”).  Review subsection “Portability”
              above.

       • Do I ever need to use an empty macro argument ("")?
              Probably not.  When this seems necessary,  often  a  shorter  or
              clearer alternative is available.

                     Instead of...               ...should be considered.
              ────────────────────────────────────────────────────────────────
              .TP ""                         .TP
              ────────────────────────────────────────────────────────────────
              .BI "" italic‐text bold‐text   .IB italic‐text bold‐text
              ────────────────────────────────────────────────────────────────
              .TH foo 1 "" "foo 1.2.3"       .TH foo 1 yyyy‐mm‐dd "foo 1.2.3"
              ────────────────────────────────────────────────────────────────
              .IP "" 4n                      .IP
              ────────────────────────────────────────────────────────────────
              .IP "" 4n                      .RS 4n
              paragraph                      .P
              ...                            paragraph
              ...                            .RE
              ────────────────────────────────────────────────────────────────
              .B one two "" three            .B one two three

              In the title heading (.TH), the date of the page’s last revision
              is  more  important than packaging information; it should not be
              omitted.  Ideally, a page maintainer will keep both up to date.

              .IP is sometimes ill‐understood and misused, especially when  no
              marker  argument  is supplied—an indentation argument is not re‐
              quired.  By setting an explicit indentation, you may be overrid‐
              ing the reader’s preference as set with  the  -rIN  option.   If
              your  page renders adequately without one, use the simpler form.
              If you need to indent multiple (unmarked)  paragraphs,  consider
              setting an inset region with .RS and .RE instead.

              In  the last example, the empty argument does have a subtly dif‐
              ferent effect than its suggested replacement: the empty argument
              causes an additional space character to be interpolated  between
              the  arguments  “two”  and  “three”—but it is a regular breaking
              space, so it can be discarded at the end of an output line.   It
              is  better  not to be subtle, particularly with space, which can
              be overlooked in source and rendered forms.

       • .RS doesn’t indent relative to my indented paragraph.
              The .RS macro sets the left margin; that  is,  the  position  at
              which  an  ordinary paragraph (.P and its synonyms) will be set.
              .IP, .TP, and the deprecated .HP use the same  default  indenta‐
              tion.   If  not  given an argument, .RS moves the left margin by
              this same amount.  To create an inset relative  to  an  indented
              paragraph,  call  .RS repeatedly until an acceptable indentation
              is achieved, or give .RS an  indentation  argument  that  is  at
              least  as much as the paragraph’s indentation amount relative to
              an adjacent .P paragraph.  See subsection “Horizontal and verti‐
              cal spacing” above for the values.

              Another approach you can use with tagged paragraphs is to  place
              an  .RS call immediately after the paragraph tag; this will also
              force a break regardless of the width of the tag, which some au‐
              thors prefer.  Follow‐up paragraphs under the tag  can  then  be
              set  with .P instead of .IP.  Remember to use .RE to end the in‐
              dented region before starting the next tagged paragraph (at  the
              appropriate nesting level).

       • .RE doesn’t move the inset back to the expected level.
       • warning: scaling unit invalid in context
       • warning: register 'an-saved-marginn' not defined
       • warning: register 'an-saved-prevailing-indentn' not defined
              The  .RS  macro  takes an indentation amount as an argument; the
              .RE macro’s argument is a specific inset level.  .RE 1  goes  to
              the  level  before any .RS macros were called, .RE 2 goes to the
              level of the first .RS call you made, and so forth.  If you  de‐
              sire  symmetry in your macro calls, simply issue one .RE without
              an argument for each .RS that precedes it.

              After calls to the .SH and .SS sectioning macros,  all  relative
              insets  are cleared and calls to .RE have no effect until .RS is
              used again.

       • Do I need to keep typing the indentation in a series of .IP calls?
              Not if you don’t want to change it.  Review subsection “Horizon‐
              tal and vertical spacing” above.

                Instead of...     ...should be considered.
              ─────────────────────────────────────────────
              .IP \(bu 4n         .IP \(bu 4n
              paragraph           paragraph
              .IP \(bu 4n         .IP \(bu
              another‐paragraph   another‐paragraph
              ─────────────────────────────────────────────

       • Why doesn’t the package provide a string to insert an ellipsis?
              Examples of ellipsis usage are shown above, in subsection  “Com‐
              mand  synopsis  macros”.   The  idiomatic roff ellipsis is three
              dots (periods) with thin space escape  sequences  \|  internally
              separating  them.   Since  dots both begin control lines and are
              candidate end‐of‐sentence characters, however, it  is  sometimes
              necessary  to  prefix  and/or  suffix an ellipsis with the dummy
              character escape sequence \&.  That fact stands even if a string
              is defined to contain the sequence; further, if the string  ends
              with  \&, end‐of‐sentence detection is defeated when you use the
              string at the end of an actual  sentence.   (Ending  a  sentence
              with  an ellipsis is often poor style, but not always.)  A hypo‐
              thetical string EL that  contained  an  ellipsis,  but  not  the
              trailing dummy character \&, would then need to be suffixed with
              the latter when not ending a sentence.

                  Instead of...              ...do this.
              ──────────────────────────────────────────────────
              .ds EL \&.\|.\|.         Arguments are
              Arguments are            .IR src‐file\~ .\|.\|.\&
              .IR src‐file\~ \*(EL\&   .IR dest‐dir .
              .IR dest‐dir .
              ──────────────────────────────────────────────────

              The  first column practices a false economy; the savings in typ‐
              ing is offset by the cost of obscuring even the suggestion of an
              ellipsis to a casual reader of the source document, and  reduced
              portability  to  non‐roff man page formatters that cannot handle
              string definitions.

              There is an ellipsis code point in Unicode, and some fonts  have
              an  ellipsis glyph, which some man pages have accessed in a non‐
              portable way with the font‐dependent  \N  escape  sequence.   We
              discourage  the  use  of these; on terminals, they may crowd the
              dots into a half‐width character cell, and will  not  render  at
              all if the output device doesn’t have the glyph.  In syntax syn‐
              opses,  missing  ellipses  can  cause great confusion.  Dots and
              space are universally supported.

Authors
       The initial GNU implementation of the man macro package was written  by
       James  Clark.   Later,  Werner Lemberg ⟨wl@gnu.org⟩ supplied the S, LT,
       and cR registers, the last a 4.3BSD‐Reno mdoc(7) feature.  Larry Kollar
       ⟨kollar@alltel.net⟩ added the FT, HY, and SN registers; the HF  string;
       and  the  PT  and  BT macros.  G. Branden Robinson ⟨g.branden.robinson@
       gmail.com⟩ implemented the AD and MF strings; CS, CT, and U  registers;
       and the MR macro.  Except for .SB, the extension macros were written by
       Lemberg, Eric S. Raymond ⟨esr@thyrsus.com⟩, and Robinson.

       This document was originally written for the Debian GNU/Linux system by
       Susan  G.  Kleinmann ⟨sgk@debian.org⟩.  It was corrected and updated by
       Lemberg and Robinson.  The extension macros were documented by  Raymond
       and  Robinson.   Raymond  also  originated  the portability section, to
       which Ingo Schwarze ⟨schwarze@usta.de⟩ contributed most of the material
       on escape sequences.

See also
       tbl(1), eqn(1), and refer(1) are preprocessors  used  with  man  pages.
       man(1)  describes the man page librarian on your system.  groff_mdoc(7)
       details the groff version of the BSD‐originated alternative macro pack‐
       age for man pages.

       groff_man(7), groff(7), groff_char(7), man(7)

groff 1.23.0                     16 July 2023               groff_man_style(7)
───────────────────────────────────────────────────────────────────────────────
groff_mdoc(7)           Miscellaneous Information Manual         groff_mdoc(7)

Name
       groff_mdoc — compose BSD‐style manual (man) pages with GNU roff

Synopsis
       groff -mdoc file ...

Description
       The GNU implementation of  the  mdoc  macro  package  is  part  of  the
       groff(1)  document  formatting system.  mdoc is a structurally‐ and se‐
       mantically‐oriented  package  for  writing  Unix  manual   pages   with
       troff(1).   Its  predecessor,  the  man(7) package, primarily addressed
       page layout and presentational concerns, leaving the selection of fonts
       and other typesetting details to the individual author.   This  discre‐
       tion has led to divergent styling practices among authors using it.

       mdoc organizes its macros into domains.  The page structure domain lays
       out  the  page  and  comprises  titles, section headings, displays, and
       lists.  The general text domain supplies macros to quote or style text,
       or to interpolate common noun phrases.  The manual domain offers seman‐
       tic macros corresponding to the terminology used  by  practitioners  in
       discussion of Unix commands, routines, and files.  Manual domain macros
       distinguish  command‐line  arguments and options, function names, func‐
       tion parameters, pathnames, variables, cross references to other manual
       pages, and so on.  These terms are meaningful both to  the  author  and
       the readers of a manual page.  It is hoped that the resulting increased
       consistency  of  the  man page corpus will enable easier translation to
       future documentation tools.

       Throughout Unix documentation, a manual entry is referred to simply  as
       a  “man  page”, regardless of its length, without gendered implication,
       and irrespective of the macro package selected for its composition.

Getting started
       The mdoc package attempts to simplify man page authorship  and  mainte‐
       nance  without  requiring  mastery of the roff language.  This document
       presents only essential facts about roff. For further  background,  in‐
       cluding  a  discussion of basic typographical concepts like “breaking”,
       “filling”, and “adjustment”, see roff(7).  Specialized  units  of  mea‐
       surement  also arise, namely ens, vees, inches, and points, abbreviated
       “n”, “v”, “i”, and “p”, respectively;  see  section  “Measurements”  of
       groff(7).

       For  brief  examples, we employ an arrow notation illustrating a trans‐
       formation of input on the left to rendered output on the  right.   Con‐
       sider the .Dq macro, which double‐quotes its arguments.
             .Dq man page  → “man page”

   Usage
       An  mdoc  macro  is  called  by placing the roff control character, ‘.’
       (dot) at the beginning of a line followed by its name.  In  this  docu‐
       ment,  we  often discuss a macro name with this leading dot to identify
       it clearly, but the dot is not part of its name.  Space or tab  charac‐
       ters  can  separate the dot from the macro name.  Arguments may follow,
       separated from the macro name and each other by spaces, but  not  tabs.
       The dot at the beginning of the line prepares the formatter to expect a
       macro  name.   A dot followed immediately by a newline is ignored; this
       is called the empty request.  To begin an input line with a dot  (or  a
       neutral  apostrophe  ‘'’) in some context other than a macro call, pre‐
       cede it with the ‘\&’ escape sequence; this is a dummy  character,  not
       formatted  for  output.  The backslash is the roff escape character; it
       can appear anywhere and it always followed by at least one more charac‐
       ter.  If followed by a newline, the backslash escapes  the  input  line
       break; you can thus keep input lines to a reasonable length without af‐
       fecting their interpretation.

       Macros  in  GNU  troff accept an unlimited number of arguments, in con‐
       trast to other troffs that often can’t handle more than nine.  In  lim‐
       ited  cases,  arguments  may be continued or extended on the next input
       line without resort to the ‘\newline’ escape sequence;  see  subsection
       “Extended  arguments”  below.   Neutral  double quotes " can be used to
       group multiple words into an argument; see  subsection  “Passing  space
       characters in an argument” below.

       Most  of mdoc’s general text and manual domain macros parse their argu‐
       ment lists for callable macro names.  This means that  an  argument  in
       the  list  matching a general text or manual domain macro name (and de‐
       fined to be callable) will be called with the remaining arguments  when
       it is encountered.  In such cases, the argument, although the name of a
       macro, is not preceded by a dot.  Macro calls can thus be nested.  This
       approach to macro argument processing is a unique characteristic of the
       mdoc package, not a general feature of roff syntax.

       For  example,  the  option  macro,  .Op, may call the flag and argument
       macros, .Fl and .Ar, to specify an optional flag with an argument.
             .Op Fl s Ar bytes      → [-s bytes]
       To prevent a word from being interpreted as a macro  name,  precede  it
       with the dummy character.
             .Op \&Fl s \&Ar bytes  → [Fl s Ar bytes]

       In  this  document, macros whose argument lists are parsed for callable
       arguments are referred to as parsed, and those that may be called  from
       an  argument list are referred to as callable.  This usage is a techni‐
       cal faux pas, since all mdoc macros are  in  fact  interpreted  (unless
       prevented  with  ‘\&’),  but as it is cumbersome to constantly refer to
       macros as “being able  to  call  other  macros”,  we  employ  the  term
       “parsed”  instead.  Except where explicitly stated, all mdoc macros are
       parsed and callable.

       In the following, we term an mdoc macro that  starts  a  line  (with  a
       leading  dot)  a command if a distinction from those appearing as argu‐
       ments of other macros is necessary.

   Passing space characters in an argument
       Sometimes it is desirable to give a macro an argument containing one or
       more space characters, for instance to specify a particular arrangement
       of arguments demanded by the macro.  Additionally,  quoting  multi‐word
       arguments  that  are  to  be  treated  the same makes mdoc work faster;
       macros that parse arguments do so once (at most) for each.   For  exam‐
       ple, the function command .Fn expects its first argument to be the name
       of  a  function  and any remaining arguments to be function parameters.
       Because C language standards mandate the inclusion of types and identi‐
       fiers in the parameter lists of function definitions, each ‘Fn’ parame‐
       ter after the first will be at least two words in length,  as  in  “int
       foo”.

       There  are  a few ways to embed a space in a macro argument.  One is to
       use the unadjustable  space  escape  sequence  \space.   The  formatter
       treats  this  escape sequence as if it were any other printable charac‐
       ter, and will not break a line there as it would a word space when  the
       output  line  is  full.  This method is useful for macro arguments that
       are not expected to straddle an output line boundary, but has  a  draw‐
       back:  this  space does not adjust as others do when the output line is
       formatted.  An alternative is to use the unbreakable space  escape  se‐
       quence, ‘\~’, which cannot break but does adjust.  This groff extension
       is widely but not perfectly portable.  Another method is to enclose the
       string in double quotes.
             .Fn fetch char\ *str   → fetch(char *str)
             .Fn fetch char\~*str   → fetch(char *str)
             .Fn fetch "char *str"  → fetch(char *str)
       If  the  ‘\’ before the space in the first example or the double quotes
       in the third example were omitted, ‘.Fn’ would see three arguments, and
       the result would contain an undesired comma.
             .Fn fetch char *str    → fetch(char, *str)

   Trailing space characters
       It is wise to remove trailing spaces from  the  ends  of  input  lines.
       Should  the need arise to put a formattable space at the end of a line,
       do so with the unadjustable or unbreakable space escape sequences.

   Formatting the backslash glyph
       When you need the roff escape character ‘\’ to appear  in  the  output,
       use  ‘\e’ or ‘\(rs’ instead.  Technically, ‘\e’ formats the current es‐
       cape character; it works reliably as long as no roff request is used to
       change it, which should never happen in man pages.  ‘\(rs’ is  a  groff
       special  character escape sequence that explicitly formats the “reverse
       solidus” (backslash) glyph.

   Other possible pitfalls
       groff mdoc warns when an  empty  input  line  is  found  outside  of  a
       display, a topic presented in subsection “Examples and displays” below.
       Use empty requests to space the source document for maintenance.

       Leading  spaces  cause a break and are formatted.  Avoid this behaviour
       if possible.  Similarly, do not put more than one space  between  words
       in  an  ordinary text line; they are not “normalized” to a single space
       as other text formatters might do.

       Don’t try to use the neutral double quote character  ‘"’  to  represent
       itself  in  an  argument.   Use  the  special character escape sequence
       ‘\(dq’ to format it.  Further, this glyph should not be used  for  con‐
       ventional quotation; mdoc offers several quotation macros.  See subsec‐
       tion “Enclosure and quoting macros” below.

       The  formatter  attempts to detect the ends of sentences and by default
       puts the equivalent of two spaces between sentences on the same  output
       line;  see roff(7).  To defeat this detection in a parsed list of macro
       arguments, put ‘\&’ before the punctuation mark.  Thus,
             The
             .Ql .
             character.
             .Pp
             The
             .Ql \&.
             character.
             .Pp
             .No test .
             test
             .Pp
             .No test.
             test
       gives
             The ‘’.  character

             The ‘.’ character.

             test.  test

             test. test
       as output.  As can be seen in the first and third  output  lines,  mdoc
       handles punctuation characters specially in macro arguments.  This will
       be explained in section “General syntax” below.

       A  comment in the source file of a man page can begin with ‘.\"’ at the
       start of an input line, ‘\"’ after other input, or ‘\#’  anywhere  (the
       last is a groff extension); the remainder of any such line is ignored.

A man page template
       Use mdoc to construct a man page from the following template.

             .\" The following three macro calls are required.
             .Dd date
             .Dt topic [section‐identifier [section‐keyword‐or‐title]]
             .Os [package‐or‐operating system [version‐or‐release]]
             .Sh Name
             .Nm topic
             .Nd summary‐description
             .\" The next heading is used in sections 2 and 3.
             .\" .Sh Library
             .\" The next heading is used in sections 1‐4, 6, 8, and 9.
             .Sh Synopsis
             .Sh Description
             .\" Uncomment and populate the following sections as needed.
             .\" .Sh "Implementation notes"
             .\" The next heading is used in sections 2, 3, and 9.
             .\" .Sh "Return values"
             .\" The next heading is used in sections 1, 3, 6, and 8.
             .\" .Sh Environment
             .\" .Sh Files
             .\" The next heading is used in sections 1, 6, and 8.
             .\" .Sh "Exit status"
             .\" .Sh Examples
             .\" The next heading is used in sections 1, 4, 6, 8, and 9.
             .\" .Sh Diagnostics
             .\" .Sh Compatibility
             .\" The next heading is used in sections 2, 3, 4, and 9.
             .\" .Sh Errors
             .\" .Sh "See also"
             .\" .Sh Standards
             .\" .Sh History
             .\" .Sh Authors
             .\" .Sh Caveats
             .\" .Sh Bugs

       The  first  items  in  the template are the commands .Dd, .Dt, and .Os.
       They identify the page  and  are  discussed  below  in  section  “Title
       macros”.

       The  remaining  items  in  the  template are section headings (.Sh); of
       which “Name” and “Description” are mandatory.  These headings are  dis‐
       cussed  in  section  “Page  structure  domain”,  which  follows section
       “Manual domain”.  Familiarize yourself with manual domain macros first;
       we use them to illustrate the use of page structure domain macros.

Conventions
       In the descriptions of macros below, square brackets surround  optional
       arguments.   An ellipsis (‘...’) represents repetition of the preceding
       argument zero or more times.  Alternative values  of  a  parameter  are
       separated  with  ‘|’.  If a mandatory parameter can take one of several
       alternative values, use braces to enclose the set, with spaces and  ‘|’
       separating the items.
             ztar {c | x} [-w [-y | -z]] [-f archive] member ...
       An  alternative to using braces is to separately synopsize distinct op‐
       eration modes, particularly if the list of valid optional arguments  is
       dependent on the user’s choice of a mandatory parameter.
             ztar c [-w [-y | -z]] [-f archive] member ...
             ztar x [-w [-y | -z]] [-f archive] member ...

       Most  macros  affect subsequent arguments until another macro or a new‐
       line is encountered.  For example, ‘.Li ls Bq Ar file’ doesn’t  produce
       ‘ls [file]’, but ‘ls [file]’.  Consequently, a warning message is emit‐
       ted for many commands if the first argument is itself a macro, since it
       cancels  the effect of the preceding one.  On rare occasions, you might
       want to format a word along with surrounding brackets as a literal.
             .Li "ls [file]"  → ls [file] # list any files named e, f, i, or l

       Many macros possess an implicit width, used when they are contained  in
       lists  and  displays.   If  you avoid relying on these default measure‐
       ments, you escape potential conflicts with site‐local modifications  of
       the mdoc package.  Explicit -width and -offset arguments to the .Bl and
       .Bd macros are preferable.

Title macros
       We  present  the  mandatory  title macros first due to their importance
       even though they formally belong to the page structure  domain  macros.
       They designate the topic, date of last revision, and the operating sys‐
       tem  or  software  project associated with the page.  Call each once at
       the beginning of the document.  They  populate  the  page  headers  and
       footers, which are in roff parlance termed “titles”.

       .Dd date
               This  first macro of any mdoc manual records the last modifica‐
               tion date of the document source.  Arguments  are  concatenated
               and separated with space characters.

               Historically,  date  was  written  in  U.S. traditional format,
               “Month day , year” where Month is the full month name  in  Eng‐
               lish, day an integer without a leading zero, and year the four‐
               digit  year.   This localism is not enforced, however.  You may
               prefer  ISO  8601  format,  YYYY‐MM‐DD.  A  date  of  the  form
               ‘$Mdocdate:  Month  day year $’ is also recognized.  It is used
               in OpenBSD manuals to automatically  insert  the  current  date
               when committing.

               This macro is neither callable nor parsed.

       .Dt topic [section‐identifier [section‐keyword‐or‐title]]
               topic  is  the  subject  of the man page.  A section‐identifier
               that begins with an integer in the range 1–9 or is one  of  the
               words ‘unass’, ‘draft’, or ‘paper’ selects a predefined section
               title.   This  use of “section” has nothing to do with the sec‐
               tion headings otherwise discussed in this page; it arises  from
               the organizational scheme of printed and bound Unix manuals.

               In  this  implementation,  the following titles are defined for
               integral section numbers.

                     1   General Commands Manual
                     2   System Calls Manual
                     3   Library Functions Manual
                     4   Kernel Interfaces Manual
                     5   File Formats Manual
                     6   Games Manual
                     7   Miscellaneous Information Manual
                     8   System Manager’s Manual
                     9   Kernel Developer’s Manual

               A section title may be arbitrary or one of the following abbre‐
               viations.

                     USD     User’s Supplementary Documents
                     PS1     Programmer’s Supplementary Documents
                     AMD     Ancestral Manual Documents
                     SMM     System Manager’s Manual
                     URM     User’s Reference Manual
                     PRM     Programmer’s Manual
                     KM      Kernel Manual
                     IND     Manual Master Index
                     LOCAL   Local Manual
                     CON     Contributed Software Manual

               For compatibility, ‘MMI’ can be used for ‘IND’, and  ‘LOC’  for
               ‘LOCAL’.   Values  from  the  previous table will specify a new
               section title.  If section‐keyword‐or‐title designates  a  com‐
               puter  architecture  recognized  by  groff  mdoc,  its value is
               prepended to the default section title as specified by the sec‐
               ond parameter.  By default, the following architecture keywords
               are defined.

                   acorn26, acorn32, algor, alpha, amd64, amiga, amigappc,
                   arc, arm, arm26, arm32, armish, atari, aviion, beagle,
                   bebox, cats, cesfic, cobalt, dreamcast, emips, evbarm,
                   evbmips, evbppc, evbsh3, ews4800mips, hp300, hp700, hpcarm,
                   hpcmips, hpcsh, hppa, hppa64, i386, ia64, ibmnws, iyonix,
                   landisk, loongson, luna68k, luna88k, m68k, mac68k, macppc,
                   mips, mips64, mipsco, mmeye, mvme68k, mvme88k, mvmeppc,
                   netwinder, news68k, newsmips, next68k, ofppc, palm, pc532,
                   playstation2, pmax, pmppc, powerpc, prep, rs6000,
                   sandpoint, sbmips, sgi, sgimips, sh3, shark, socppc,
                   solbourne, sparc, sparc64, sun2, sun3, tahoe, vax, x68k,
                   x86_64, xen, zaurus

               If a section title is not determined after  the  above  matches
               have been attempted, section‐keyword‐or‐title is used.

               The  effects of varying ‘.Dt’ arguments on the page header con‐
               tent are shown below.  Observe how ‘\&’ prevents the numeral  2
               from being used to look up a predefined section title.

                 .Dt foo 2       →  foo(2)     System Calls Manual      foo(2)
                 .Dt foo 2 m68k  →  foo(2)   m68k System Calls Manual   foo(2)
                 .Dt foo 2 baz   →  foo(2)     System Calls Manual      foo(2)
                 .Dt foo \&2 baz →  foo(2)             baz              foo(2)
                 .Dt foo "" baz  →  foo                baz                 foo
                 .Dt foo M Z80   →  foo(M)             Z80              foo(M)

               roff  strings  define  section  titles and architecture identi‐
               fiers.  Site‐specific additions might  be  found  in  the  file
               mdoc.local; see section “Files” below.

               This macro is neither callable nor parsed.

       .Os [operating‐system‐or‐package‐name [version‐or‐release]]
               This  macro  associates  the document with a software distribu‐
               tion.  When composing a man page to be included in the base in‐
               stallation of an operating system, do not provide an  argument;
               mdoc  will  supply it.  In this implementation, that default is
               “GNU”.  It may be overridden in the  site  configuration  file,
               mdoc.local;  see  section  “Files”  below.  A portable software
               package maintaining its own man pages can supply its  name  and
               version  number or release identifier as optional arguments.  A
               version‐or‐release argument should use the  standard  nomencla‐
               ture  for the software specified.  In the following table, rec‐
               ognized version‐or‐release arguments for some predefined  oper‐
               ating systems are listed.  As with .Dt, site additions might be
               defined in mdoc.local.

                     ATT        7th, 7, III, 3, V, V.2, V.3, V.4

                     BSD        3, 4, 4.1, 4.2, 4.3, 4.3t, 4.3T, 4.3r, 4.3R,
                                4.4

                     NetBSD     0.8, 0.8a, 0.9, 0.9a, 1.0, 1.0a, 1.1, 1.2,
                                1.2a, 1.2b, 1.2c, 1.2d, 1.2e, 1.3, 1.3a, 1.4,
                                1.4.1, 1.4.2, 1.4.3, 1.5, 1.5.1, 1.5.2, 1.5.3,
                                1.6, 1.6.1, 1.6.2, 1.6.3, 2.0, 2.0.1, 2.0.2,
                                2.0.3, 2.1, 3.0, 3.0.1, 3.0.2, 3.0.3, 3.1,
                                3.1.1, 4.0, 4.0.1, 5.0, 5.0.1, 5.0.2, 5.1,
                                5.1.2, 5.1.3, 5.1.4, 5.2, 5.2.1, 5.2.2, 6.0,
                                6.0.1, 6.0.2, 6.0.3, 6.0.4, 6.0.5, 6.0.6, 6.1,
                                6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.1.5, 7.0, 7.0.1,
                                7.0.2, 7.1, 7.1.1, 7.1.2, 7.2, 8.0, 8.1

                     FreeBSD    1.0, 1.1, 1.1.5, 1.1.5.1, 2.0, 2.0.5, 2.1,
                                2.1.5, 2.1.6, 2.1.7, 2.2, 2.2.1, 2.2.2, 2.2.5,
                                2.2.6, 2.2.7, 2.2.8, 2.2.9, 3.0, 3.1, 3.2,
                                3.3, 3.4, 3.5, 4.0, 4.1, 4.1.1, 4.2, 4.3, 4.4,
                                4.5, 4.6, 4.6.2, 4.7, 4.8, 4.9, 4.10, 4.11,
                                5.0, 5.1, 5.2, 5.2.1, 5.3, 5.4, 5.5, 6.0, 6.1,
                                6.2, 6.3, 6.4, 7.0, 7.1, 7.2, 7.3, 7.4, 8.0,
                                8.1, 8.2, 8.3, 8.4, 9.0, 9.1, 9.2, 9.3, 10.0,
                                10.1, 10.2, 10.3, 10.4, 11.0, 11.1, 11.2,
                                11.3, 12.0, 12.1

                     OpenBSD    2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8,
                                2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7,
                                3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6,
                                4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5,
                                5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4,
                                6.5, 6.6

                     DragonFly  1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,
                                1.8.1, 1.9, 1.10, 1.11, 1.12, 1.12.2, 1.13,
                                2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8,
                                2.9, 2.9.1, 2.10, 2.10.1, 2.11, 2.12, 2.13,
                                3.0, 3.0.1, 3.0.2, 3.1, 3.2, 3.2.1, 3.2.2,
                                3.3, 3.4, 3.4.1, 3.4.2, 3.4.3, 3.5, 3.6,
                                3.6.1, 3.6.2, 3.7, 3.8, 3.8.1, 3.8.2, 4.0,
                                4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.0.6, 4.1,
                                4.2, 4.2.1, 4.2.2, 4.2.3, 4.2.4, 4.3, 4.4,
                                4.4.1, 4.4.2, 4.4.3, 4.5, 4.6, 4.6.1, 4.6.2,
                                4.7, 4.8, 4.8.1, 4.9, 5.0, 5.0.1, 5.0.2, 5.1,
                                5.2, 5.2.1, 5.2.2, 5.3, 5.4, 5.4.1, 5.4.2,
                                5.4.3, 5.5, 5.6, 5.6.1, 5.6.2

                     Darwin     8.0.0, 8.1.0, 8.2.0, 8.3.0, 8.4.0, 8.5.0,
                                8.6.0, 8.7.0, 8.8.0, 8.9.0, 8.10.0, 8.11.0,
                                9.0.0, 9.1.0, 9.2.0, 9.3.0, 9.4.0, 9.5.0,
                                9.6.0, 9.7.0, 9.8.0, 10.0.0, 10.1.0, 10.2.0,
                                10.3.0, 10.4.0, 10.5.0, 10.6.0, 10.7.0,
                                10.8.0, 11.0.0, 11.1.0, 11.2.0, 11.3.0,
                                11.4.0, 11.5.0, 12.0.0, 12.1.0, 12.2.0,
                                13.0.0, 13.1.0, 13.2.0, 13.3.0, 13.4.0,
                                14.0.0, 14.1.0, 14.2.0, 14.3.0, 14.4.0,
                                14.5.0, 15.0.0, 15.1.0, 15.2.0, 15.3.0,
                                15.4.0, 15.5.0, 15.6.0, 16.0.0, 16.1.0,
                                16.2.0, 16.3.0, 16.4.0, 16.5.0, 16.6.0,
                                17.0.0, 17.1.0, 17.2.0, 17.3.0, 17.4.0,
                                17.5.0, 17.6.0, 17.7.0, 18.0.0, 18.1.0,
                                18.2.0, 18.3.0, 18.4.0, 18.5.0, 18.6.0,
                                18.7.0, 19.0.0, 19.1.0, 19.2.0

               Historically,  the first argument used with .Dt was BSD or ATT.
               An unrecognized version argument after  ATT  is  replaced  with
               “Unix”; for other predefined abbreviations, it is ignored and a
               warning  diagnostic emitted.  Otherwise, unrecognized arguments
               are displayed verbatim in the page footer.  For instance,  this
               page  uses  “.Os  groff 1.23.0” whereas a locally produced page
               might employ “.Os "UXYZ CS Department"”, omitting versioning.

               This macro is neither callable nor parsed.

Introduction to manual and general text domains
   What’s in a Name...
       The manual domain macro names are derived from the day to day  informal
       language  used  to  describe  commands,  subroutines and related files.
       Slightly different variations of this language are used to describe the
       three different aspects of writing a man page.  First, there is the de‐
       scription of mdoc macro command usage.  Second is the description of  a
       Unix  command with mdoc macros, and third, the description of a command
       to a user in the verbal sense; that is, discussion of a command in  the
       text of a man page.

       In  the  first case, troff macros are themselves a type of command; the
       general syntax for a troff command is:

             .Xx argument1 argument2 ...

       ‘.Xx’ is a macro command, and anything following it are arguments to be
       processed.  In the second case, the description of a Unix command using
       the manual domain macros is a bit more involved; a  typical  “Synopsis”
       command line might be displayed as:

             filter [-flag] ⟨infile⟩ ⟨outfile⟩

       Here,  filter  is  the command name and the bracketed string -flag is a
       flag argument designated as optional by the option brackets.   In  mdoc
       terms,  ⟨infile⟩ and ⟨outfile⟩ are called meta arguments; in this exam‐
       ple, the user has to replace the meta expressions given in angle brack‐
       ets with real file names.  Note that in this  document  meta  arguments
       are  used  to describe mdoc commands; in most man pages, meta variables
       are not specifically written with angle brackets.  The macros that for‐
       matted the above example:

             .Nm filter
             .Op Fl flag
             .Ao Ar infile Ac Ao Ar outfile Ac

       In the third case, discussion of commands and command  syntax  includes
       both  examples  above, but may add more detail.  The arguments ⟨infile⟩
       and ⟨outfile⟩ from the example above might be referred to  as  operands
       or file arguments.  Some command‐line argument lists are quite long:

             make  [-eiknqrstv] [-D variable] [-d flags] [-f makefile] [-I
                   directory] [-j max_jobs] [variable=value] [target ...]

       Here  one  might  talk about the command make and qualify the argument,
       makefile, as an argument to the flag, -f, or discuss the optional  file
       operand  target.  In the verbal context, such detail can prevent confu‐
       sion, however the mdoc package does not have a macro for an argument to
       a flag.  Instead the ‘Ar’ argument macro is used for an operand or file
       argument like target as well as an argument to a  flag  like  variable.
       The make command line was produced from:

             .Nm make
             .Op Fl eiknqrstv
             .Op Fl D Ar variable
             .Op Fl d Ar flags
             .Op Fl f Ar makefile
             .Op Fl I Ar directory
             .Op Fl j Ar max_jobs
             .Op Ar variable Ns = Ns Ar value
             .Bk
             .Op Ar target ...
             .Ek

       The ‘.Bk’ and ‘.Ek’ macros are explained in “Keeps”.

   General Syntax
       The manual domain and general text domain macros share a similar syntax
       with  a  few  minor  deviations; most notably, ‘.Ar’, ‘.Fl’, ‘.Nm’, and
       ‘.Pa’ differ only when called without arguments; and  ‘.Fn’  and  ‘.Xr’
       impose  an order on their argument lists.  All manual domain macros are
       capable of recognizing and properly handling punctuation, provided each
       punctuation character is separated by a leading space.  If a command is
       given:

             .Ar sptr, ptr),

       The result is:

             sptr, ptr),

       The punctuation is not recognized and all is output in the font used by
       ‘.Ar’.  If the punctuation is separated by a leading white space:

             .Ar sptr , ptr ) ,

       The result is:

             sptr, ptr),

       The punctuation is now recognized and output in the default  font  dis‐
       tinguishing  it from the argument strings.  To remove the special mean‐
       ing from a punctuation character, escape it with ‘\&’.

       The following punctuation characters are recognized by mdoc:

                 .         ,         :         ;         (
                 )         [         ]         ?         !

       troff is limited as a macro language, and has difficulty when presented
       with a string containing certain mathematical,  logical,  or  quotation
       character sequences:

                   {+,-,/,*,%,<,>,<=,>=,=,==,&,`,',"}

       The problem is that troff may assume it is supposed to actually perform
       the  operation  or  evaluation suggested by the characters.  To prevent
       the accidental evaluation of these characters, escape them  with  ‘\&’.
       Typical  syntax is shown in the first manual domain macro displayed be‐
       low, ‘.Ad’.

Manual domain
   Addresses
       The address macro identifies an address construct.

             Usage: .Ad ⟨address⟩ ...

                      .Ad addr1           addr1
                      .Ad addr1 .         addr1.
                      .Ad addr1 , file2   addr1, file2
                      .Ad f1 , f2 , f3 :  f1, f2, f3:
                      .Ad addr ) ) ,      addr)),

       The default width is 12n.

   Author Name
       The ‘.An’ macro is used to specify the name of the author of  the  item
       being documented, or the name of the author of the actual manual page.

             Usage: .An ⟨author name⟩ ...

                      .An "Joe Author"        Joe Author

                      .An "Joe Author" ,      Joe Author,

                      .An "Joe Author" Aq nobody@FreeBSD.org
                                              Joe Author <nobody@FreeBSD.org>

                      .An "Joe Author" ) ) ,  Joe Author)),

       The default width is 12n.

       In  a  section titled “Authors”, ‘An’ causes a break, allowing each new
       name to appear on its own line.  If this is not desirable,

             .An -nosplit

       call will turn this off.  To turn splitting back on, write

             .An -split

   Arguments
       The .Ar argument macro may be used whenever an argument is  referenced.
       If called without arguments, ‘file ...’ is output.  This places the el‐
       lipsis  in italics, which is ugly and incorrect, and will be noticed on
       terminals that underline text instead of using an oblique typeface.  We
       recommend using ‘.Ar file No ...’ instead.

             Usage: .Ar [⟨argument⟩] ...

                      .Ar              file ...
                      .Ar file No ...  file ...
                      .Ar file1        file1
                      .Ar file1 .      file1.
                      .Ar file1 file2  file1 file2
                      .Ar f1 f2 f3 :   f1 f2 f3:
                      .Ar file ) ) ,   file)),

       The default width is 12n.

   Configuration Declaration (Section Four Only)
       The ‘.Cd’ macro is used to demonstrate a config(8)  declaration  for  a
       device interface in a section four manual.

             Usage: .Cd ⟨argument⟩ ...

                      .Cd "device le0 at scode?"  device le0 at scode?

       In  a  section  titled “Synopsis”, ‘Cd’ causes a break before and after
       its arguments.

       The default width is 12n.

   Command Modifiers
       The command modifier is identical to the ‘.Fl’ (flag) command with  the
       exception that the ‘.Cm’ macro does not assert a dash in front of every
       argument.   Traditionally  flags are marked by the preceding dash, how‐
       ever, some commands or subsets of commands do not  use  them.   Command
       modifiers  may  also  be specified in conjunction with interactive com‐
       mands such as editor commands.  See “Flags”.

       The default width is 10n.

   Defined Variables
       A variable (or constant) that is defined in an include file  is  speci‐
       fied by the macro ‘.Dv’.

             Usage: .Dv ⟨defined‐variable⟩ ...

                      .Dv MAXHOSTNAMELEN  MAXHOSTNAMELEN
                      .Dv TIOCGPGRP )     TIOCGPGRP)

       The default width is 12n.

   Errnos
       The  ‘.Er’  errno macro specifies the error return value for section 2,
       3, and 9 library routines.  The second example below shows  ‘.Er’  used
       with the ‘.Bq’ general text domain macro, as it would be used in a sec‐
       tion two manual page.

             Usage: .Er ⟨errno type⟩ ...

                      .Er ENOENT      ENOENT
                      .Er ENOENT ) ;  ENOENT);
                      .Bq Er ENOTDIR  [ENOTDIR]

       The default width is 17n.

   Environment Variables
       The ‘.Ev’ macro specifies an environment variable.

             Usage: .Ev ⟨argument⟩ ...

                      .Ev DISPLAY        DISPLAY
                      .Ev PATH .         PATH.
                      .Ev PRINTER ) ) ,  PRINTER)),

       The default width is 15n.

   Flags
       The  ‘.Fl’  macro handles command‐line flags.  It prepends a dash, ‘-’,
       to the flag.  For interactive command flags that are not prepended with
       a dash, the ‘.Cm’ (command modifier) macro is  identical,  but  without
       the dash.

             Usage: .Fl ⟨argument⟩ ...

                      .Fl          -
                      .Fl cfv      -cfv
                      .Fl cfv .    -cfv.
                      .Cm cfv .    cfv.
                      .Fl s v t    -s -v -t
                      .Fl - ,      --,
                      .Fl xyz ) ,  -xyz),
                      .Fl |        - |

       The  ‘.Fl’  macro  without any arguments results in a dash representing
       stdin/stdout.  Note that giving ‘.Fl’ a single dash will result in  two
       dashes.

       The default width is 12n.

   Function Declarations
       The  ‘.Fd’  macro is used in the “Synopsis” section with section two or
       three functions.  It is neither callable nor parsed.

             Usage: .Fd ⟨argument⟩ ...

                      .Fd "#include <sys/types.h>"  #include <sys/types.h>

       In a section titled “Synopsis”, ‘Fd’ causes a break if a  function  has
       already  been  presented and a break has not occurred, leaving vertical
       space between one function declaration and the next.

       In a section titled “Synopsis”, the ‘In’ macro represents the  #include
       statement,  and  is  the short form of the above example.  It specifies
       the C header file as being included in a C program.  It also  causes  a
       break.

       While  not in the “Synopsis” section, it represents the header file en‐
       closed in angle brackets.

             Usage: .In ⟨header file⟩

                      .In stdio.h  <stdio.h>
                      .In stdio.h  <stdio.h>

   Function Types
       This macro is intended for the “Synopsis” section.  It may be used any‐
       where else in the man page without problems, but its main purpose is to
       present  the  function  type  (in  BSD  kernel  normal  form)  for  the
       “Synopsis” of sections two and three.  (It causes a break, allowing the
       function name to appear on the next line.)

             Usage: .Ft ⟨type⟩ ...

                      .Ft struct stat  struct stat

   Functions (Library Routines)
       The ‘.Fn’ macro is modeled on ANSI C conventions.

             Usage: .Fn ⟨function⟩ [⟨parameter⟩] ...

                      .Fn getchar              getchar()
                      .Fn strlen ) ,           strlen()),
                      .Fn align "char *ptr" ,  align(char *ptr),

       Note  that  any call to another macro signals the end of the ‘.Fn’ call
       (it will insert a closing parenthesis at that point).

       For functions with many parameters (which is rare),  the  macros  ‘.Fo’
       (function  open)  and  ‘.Fc’  (function  close)  may be used with ‘.Fa’
       (function argument).

       Example:

             .Ft int
             .Fo res_mkquery
             .Fa "int op"
             .Fa "char *dname"
             .Fa "int class"
             .Fa "int type"
             .Fa "char *data"
             .Fa "int datalen"
             .Fa "struct rrec *newrr"
             .Fa "char *buf"
             .Fa "int buflen"
             .Fc

       Produces:

             int res_mkquery(int op, char *dname, int class, int type,
             char *data, int datalen, struct rrec *newrr, char *buf,
             int buflen)

       Typically, in a “Synopsis” section, the function delcaration will begin
       the line.  If more than one function is  presented  in  the  “Synopsis”
       section  and  a  function  type has not been given, a break will occur,
       leaving vertical space between the current and prior function names.

       The default width values of ‘.Fn’ and ‘.Fo’ are 12n  and  16n,  respec‐
       tively.

   Function Arguments
       The  ‘.Fa’  macro  is  used to refer to function arguments (parameters)
       outside  of  the  “Synopsis”  section  of  the  manual  or  inside  the
       “Synopsis”  section  if the enclosure macros ‘.Fo’ and ‘.Fc’ instead of
       ‘.Fn’ are used.  ‘.Fa’ may also be used to refer to structure members.

             Usage: .Fa ⟨function argument⟩ ...

                      .Fa d_namlen ) ) ,  d_namlen)),
                      .Fa iov_len         iov_len

       The default width is 12n.

   Return Values
       The ‘.Rv’ macro generates text for use in the “Return values” section.

             Usage: .Rv [-std] [⟨function⟩ ...]

       For example, ‘.Rv -std atexit’ produces:

             The atexit() function returns the value 0 if successful; other‐
             wise the value -1 is returned and the global variable errno is
             set to indicate the error.

       The -std option is valid only for manual page sections 2 and  3.   Cur‐
       rently, this macro does nothing if used without the -std flag.

   Exit Status
       The ‘.Ex’ macro generates text for use in the “Diagnostics” section.

             Usage: .Ex [-std] [⟨utility⟩ ...]

       For example, ‘.Ex -std cat’ produces:

             The cat utility exits 0 on success, and >0 if an error occurs.

       The  -std  option  is  valid  only for manual page sections 1, 6 and 8.
       Currently, this macro does nothing if used without the -std flag.

   Interactive Commands
       The ‘.Ic’ macro designates an interactive or internal command.

             Usage: .Ic ⟨argument⟩ ...

                      .Ic :wq                :wq
                      .Ic "do while {...}"   do while {...}
                      .Ic setenv , unsetenv  setenv, unsetenv

       The default width is 12n.

   Library Names
       The ‘.Lb’ macro is used to specify the library where a particular func‐
       tion is compiled in.

             Usage: .Lb ⟨argument⟩ ...

       Available arguments to ‘.Lb’ and their results are:

             libarchive     Reading and  Writing  Streaming  Archives  Library
                            (libarchive, -larchive)
             libarm         ARM Architecture Library (libarm, -larm)
             libarm32       ARM32 Architecture Library (libarm32, -larm32)
             libbluetooth   Bluetooth Library (libbluetooth, -lbluetooth)
             libbsm         Basic Security Module Library (libbsm, -lbsm)
             libc           Standard C Library (libc, -lc)
             libc_r         Reentrant C Library (libc_r, -lc_r)
             libcalendar    Calendar    Arithmetic    Library    (libcalendar,
                            -lcalendar)
             libcam         Common Access Method User Library (libcam, -lcam)
             libcdk         Curses Development Kit Library (libcdk, -lcdk)
             libcipher      FreeSec Crypt Library (libcipher, -lcipher)
             libcompat      Compatibility Library (libcompat, -lcompat)
             libcrypt       Crypt Library (libcrypt, -lcrypt)
             libcurses      Curses Library (libcurses, -lcurses)
             libdevinfo     Device and Resource  Information  Utility  Library
                            (libdevinfo, -ldevinfo)
             libdevstat     Device Statistics Library (libdevstat, -ldevstat)
             libdisk        Interface  to  Slice  and Partition Labels Library
                            (libdisk, -ldisk)
             libdwarf       DWARF Access Library (libdwarf, -ldwarf)
             libedit        Command Line Editor Library (libedit, -ledit)
             libelf         ELF Access Library (libelf, -lelf)
             libevent       Event Notification Library (libevent, -levent)
             libfetch       File Transfer Library for URLs (libfetch, -lfetch)
             libform        Curses Form Library (libform, -lform)
             libgeom        Userland API Library  for  kernel  GEOM  subsystem
                            (libgeom, -lgeom)
             libgpib        General‐Purpose   Instrument  Bus  (GPIB)  library
                            (libgpib, -lgpib)
             libi386        i386 Architecture Library (libi386, -li386)
             libintl        Internationalized   Message    Handling    Library
                            (libintl, -lintl)
             libipsec       IPsec Policy Control Library (libipsec, -lipsec)
             libipx         IPX  Address  Conversion  Support Library (libipx,
                            -lipx)
             libiscsi       iSCSI protocol library (libiscsi, -liscsi)
             libjail        Jail Library (libjail, -ljail)
             libkiconv      Kernel side iconv library (libkiconv, -lkiconv)
             libkse         N:M Threading Library (libkse, -lkse)
             libkvm         Kernel Data Access Library (libkvm, -lkvm)
             libm           Math Library (libm, -lm)
             libm68k        m68k Architecture Library (libm68k, -lm68k)
             libmagic       Magic  Number   Recognition   Library   (libmagic,
                            -lmagic)
             libmd          Message  Digest  (MD4,  MD5, etc.) Support Library
                            (libmd, -lmd)
             libmemstat     Kernel   Memory   Allocator   Statistics   Library
                            (libmemstat, -lmemstat)
             libmenu        Curses Menu Library (libmenu, -lmenu)
             libnetgraph    Netgraph User Library (libnetgraph, -lnetgraph)
             libnetpgp      Netpgp   signing,   verification,  encryption  and
                            decryption (libnetpgp, -lnetpgp)
             libossaudio    OSS   Audio   Emulation   Library    (libossaudio,
                            -lossaudio)
             libpam         Pluggable  Authentication  Module Library (libpam,
                            -lpam)
             libpcap        Packet Capture Library (libpcap, -lpcap)
             libpci         PCI Bus Access Library (libpci, -lpci)
             libpmc         Performance Counters Library (libpmc, -lpmc)
             libposix       POSIX Compatibility Library (libposix, -lposix)
             libprop        Property  Container   Object   Library   (libprop,
                            -lprop)
             libpthread     POSIX Threads Library (libpthread, -lpthread)
             libpuffs       puffs Convenience Library (libpuffs, -lpuffs)
             librefuse      File   System  in  Userspace  Convenience  Library
                            (librefuse, -lrefuse)
             libresolv      DNS Resolver Library (libresolv, -lresolv)
             librpcsec_gss  RPC GSS‐API Authentication Library (librpcsec_gss,
                            -lrpcsec_gss)
             librpcsvc      RPC Service Library (librpcsvc, -lrpcsvc)
             librt          POSIX Real‐time Library (librt, -lrt)
             libsdp         Bluetooth Service Discovery Protocol User  Library
                            (libsdp, -lsdp)
             libssp         Buffer Overflow Protection Library (libssp, -lssp)
             libSystem      System Library (libSystem, -lSystem)
             libtermcap     Termcap Access Library (libtermcap, -ltermcap)
             libterminfo    Terminal    Information    Library   (libterminfo,
                            -lterminfo)
             libthr         1:1 Threading Library (libthr, -lthr)
             libufs         UFS File System Access Library (libufs, -lufs)
             libugidfw      File System Firewall Interface Library (libugidfw,
                            -lugidfw)
             libulog        User Login Record Library (libulog, -lulog)
             libusbhid      USB Human Interface  Devices  Library  (libusbhid,
                            -lusbhid)
             libutil        System Utilities Library (libutil, -lutil)
             libvgl         Video Graphics Library (libvgl, -lvgl)
             libx86_64      x86_64 Architecture Library (libx86_64, -lx86_64)
             libz           Compression Library (libz, -lz)

       Site‐specific additions might be found in the file mdoc.local; see sec‐
       tion “Files” below.

       In a section titled “Library”, ‘Lb’ causes a break before and after its
       arguments.

   Literals
       The  ‘Li’  literal  macro  may be used for special characters, symbolic
       constants, and other syntactical items that should be typed exactly  as
       displayed.

             Usage: .Li ⟨argument⟩ ...

                      .Li \en          \n
                      .Li M1 M2 M3 ;   M1 M2 M3;
                      .Li cntrl-D ) ,  cntrl‐D),
                      .Li 1024 ...     1024 ...

       The default width is 16n.

   Names
       The  ‘Nm’ macro is used for the document title or page topic.  Upon its
       first call, it has the peculiarity of remembering its  argument,  which
       should  always  be the topic of the man page.  When subsequently called
       without arguments, ‘Nm’ regurgitates this initial  name  for  the  sole
       purpose of making less work for the author.  Use of ‘Nm’ is also appro‐
       priate  when  presenting a command synopsis for the topic of a man page
       in section 1, 6, or 8.  Its behavior changes when presented with  argu‐
       ments of various forms.

                      .Nm groff_mdoc  groff_mdoc
                      .Nm             groff_mdoc
                      .Nm \-mdoc      -mdoc
                      .Nm foo ) ) ,   foo)),
                      .Nm :           groff_mdoc:

       By  default,  the  topic is set in boldface to reflect its prime impor‐
       tance in the discussion.  Cross references to  other  man  page  topics
       should use ‘Xr’; including a second argument for the section number en‐
       ables  them to be hyperlinked.  By default, cross‐referenced topics are
       set in italics to avoid cluttering the page with boldface.

       The default width is 10n.

   Options
       The ‘.Op’ macro places option brackets around any  remaining  arguments
       on  the  command  line, and places any trailing punctuation outside the
       brackets.  The macros ‘.Oo’ and ‘.Oc’ (which produce an opening  and  a
       closing  option  bracket,  respectively) may be used across one or more
       lines or to specify the exact position of the closing parenthesis.

             Usage: .Op [⟨option⟩] ...

                      .Op                                []
                      .Op Fl k                           [-k]
                      .Op Fl k ) .                       [-k]).
                      .Op Fl k Ar kookfile               [-k kookfile]
                      .Op Fl k Ar kookfile ,             [-k kookfile],
                      .Op Ar objfil Op Ar corfil         [objfil [corfil]]
                      .Op Fl c Ar objfil Op Ar corfil ,  [-c objfil [corfil]],
                      .Op word1 word2                    [word1 word2]
                      .Li .Op Oo Ao option Ac Oc ...     .Op [⟨option⟩] ...

       Here a typical example of the ‘.Oo’ and ‘.Oc’ macros:

             .Oo
             .Op Fl k Ar kilobytes
             .Op Fl i Ar interval
             .Op Fl c Ar count
             .Oc

       Produces:

             [[-k kilobytes] [-i interval] [-c count]]

       The default width values of ‘.Op’ and ‘.Oo’ are 14n  and  10n,  respec‐
       tively.

   Pathnames
       The  ‘.Pa’  macro formats file specifications.  If called without argu‐
       ments, ‘~’ (recognized by many  shells)  is  output,  representing  the
       user’s home directory.

             Usage: .Pa [⟨pathname⟩] ...

                      .Pa                    ~
                      .Pa /usr/share         /usr/share
                      .Pa /tmp/fooXXXXX ) .  /tmp/fooXXXXX).

       The default width is 32n.

   Standards
       The  ‘.St’  macro  replaces  standard  abbreviations  with their formal
       names.

             Usage: .St ⟨abbreviation⟩ ...

       Available pairs for “Abbreviation/Formal Name” are:

       ANSI/ISO C

             -ansiC          ANSI X3.159‐1989 (“ANSI C89”)
             -ansiC-89       ANSI X3.159‐1989 (“ANSI C89”)
             -isoC           ISO/IEC 9899:1990 (“ISO C90”)
             -isoC-90        ISO/IEC 9899:1990 (“ISO C90”)
             -isoC-99        ISO/IEC 9899:1999 (“ISO C99”)
             -isoC-2011      ISO/IEC 9899:2011 (“ISO C11”)

       POSIX Part 1: System API

             -iso9945-1-90   ISO/IEC 9945‐1:1990 (“POSIX.1”)
             -iso9945-1-96   ISO/IEC 9945‐1:1996 (“POSIX.1”)
             -p1003.1        IEEE Std 1003.1 (“POSIX.1”)
             -p1003.1-88     IEEE Std 1003.1‐1988 (“POSIX.1”)
             -p1003.1-90     ISO/IEC 9945‐1:1990 (“POSIX.1”)
             -p1003.1-96     ISO/IEC 9945‐1:1996 (“POSIX.1”)
             -p1003.1b-93    IEEE Std 1003.1b‐1993 (“POSIX.1”)
             -p1003.1c-95    IEEE Std 1003.1c‐1995 (“POSIX.1”)
             -p1003.1g-2000  IEEE Std 1003.1g‐2000 (“POSIX.1”)
             -p1003.1i-95    IEEE Std 1003.1i‐1995 (“POSIX.1”)
             -p1003.1-2001   IEEE Std 1003.1‐2001 (“POSIX.1”)
             -p1003.1-2004   IEEE Std 1003.1‐2004 (“POSIX.1”)
             -p1003.1-2008   IEEE Std 1003.1‐2008 (“POSIX.1”)

       POSIX Part 2: Shell and Utilities

             -iso9945-2-93   ISO/IEC 9945‐2:1993 (“POSIX.2”)
             -p1003.2        IEEE Std 1003.2 (“POSIX.2”)
             -p1003.2-92     IEEE Std 1003.2‐1992 (“POSIX.2”)
             -p1003.2a-92    IEEE Std 1003.2a‐1992 (“POSIX.2”)

       X/Open

             -susv1          Version  1  of  the  Single  UNIX   Specification
                             (“SUSv1”)
             -susv2          Version   2  of  the  Single  UNIX  Specification
                             (“SUSv2”)
             -susv3          Version  3  of  the  Single  UNIX   Specification
                             (“SUSv3”)
             -susv4          Version   4  of  the  Single  UNIX  Specification
                             (“SUSv4”)
             -svid4          System V  Interface  Definition,  Fourth  Edition
                             (“SVID4”)
             -xbd5           X/Open Base Definitions Issue 5 (“XBD5”)
             -xcu5           X/Open Commands and Utilities Issue 5 (“XCU5”)
             -xcurses4.2     X/Open Curses Issue 4, Version 2 (“XCURSES4.2”)
             -xns5           X/Open Networking Services Issue 5 (“XNS5”)
             -xns5.2         X/Open Networking Services Issue 5.2 (“XNS5.2”)
             -xpg3           X/Open Portability Guide Issue 3 (“XPG3”)
             -xpg4           X/Open Portability Guide Issue 4 (“XPG4”)
             -xpg4.2         X/Open  Portability  Guide  Issue  4,  Version  2
                             (“XPG4.2”)
             -xsh5           X/Open System  Interfaces  and  Headers  Issue  5
                             (“XSH5”)

       Miscellaneous

             -ieee754        IEEE Std 754‐1985
             -iso8601        ISO 8601
             -iso8802-3      ISO/IEC 8802‐3:1989

   Variable Types
       The  ‘.Vt’  macro may be used whenever a type is referenced.  In a sec‐
       tion titled “Synopsis”, ‘Vt’ causes a break  (useful  for  old‐style  C
       variable declarations).

             Usage: .Vt ⟨type⟩ ...

                      .Vt extern char *optarg ;  extern char *optarg;
                      .Vt FILE *                 FILE *

   Variables
       Generic variable reference.

             Usage: .Va ⟨variable⟩ ...

                      .Va count             count
                      .Va settimer ,        settimer,
                      .Va "int *prt" ) :    int *prt):
                      .Va "char s" ] ) ) ,  char s])),

       The default width is 12n.

   Manual Page Cross References
       The  ‘.Xr’  macro  expects the first argument to be a manual page name.
       The optional second argument, if a string  (defining  the  manual  sec‐
       tion), is put into parentheses.

             Usage: .Xr ⟨man page name⟩ [⟨section⟩] ...

                      .Xr mdoc        mdoc
                      .Xr mdoc ,      mdoc,
                      .Xr mdoc 7      mdoc(7)
                      .Xr xinit 1x ;  xinit(1x);

       The default width is 10n.

General text domain
   AT&T Macro
             Usage: .At [⟨version⟩] ...

                      .At       AT&T UNIX
                      .At v6 .  Version 6 AT&T UNIX.

       The following values for ⟨version⟩ are possible:

             32v, v1, v2, v3, v4, v5, v6, v7, III, V, V.1, V.2, V.3, V.4

   BSD Macro
             Usage: .Bx {-alpha | -beta | -devel} ...
                    .Bx [⟨version⟩ [⟨release⟩]] ...

                      .Bx         BSD
                      .Bx 4.3 .   4.3BSD.
                      .Bx -devel  BSD (currently under development)

       ⟨version⟩  will be prepended to the string ‘BSD’.  The following values
       for ⟨release⟩ are possible:

             Reno, reno, Tahoe, tahoe, Lite, lite, Lite2, lite2

   NetBSD Macro
             Usage: .Nx [⟨version⟩] ...

                      .Nx        NetBSD
                      .Nx 1.4 .  NetBSD 1.4.

       For possible values of ⟨version⟩ see the description of the ‘.Os’  com‐
       mand above in section “Title macros”.

   FreeBSD Macro
             Usage: .Fx [⟨version⟩] ...

                      .Fx        FreeBSD
                      .Fx 2.2 .  FreeBSD 2.2.

       For  possible values of ⟨version⟩ see the description of the ‘.Os’ com‐
       mand above in section “Title macros”.

   DragonFly Macro
             Usage: .Dx [⟨version⟩] ...

                      .Dx        DragonFly
                      .Dx 1.4 .  DragonFly 1.4.

       For possible values of ⟨version⟩ see the description of the ‘.Os’  com‐
       mand above in section “Title macros”.

   OpenBSD Macro
             Usage: .Ox [⟨version⟩] ...

                      .Ox 1.0  OpenBSD 1.0

   BSD/OS Macro
             Usage: .Bsx [⟨version⟩] ...

                      .Bsx 1.0  BSD/OS 1.0

   Unix Macro
             Usage: .Ux ...

                      .Ux  Unix

   Emphasis Macro
       Text  may  be  stressed  or emphasized with the ‘.Em’ macro.  The usual
       font for emphasis is italic.

             Usage: .Em ⟨argument⟩ ...

                      .Em does not          does not
                      .Em exceed 1024 .     exceed 1024.
                      .Em vide infra ) ) ,  vide infra)),

       The default width is 10n.

   Font Mode
       The ‘.Bf’ font mode must be ended with  the  ‘.Ef’  macro  (the  latter
       takes no arguments).  Font modes may be nested within other font modes.

       ‘.Bf’ has the following syntax:

             .Bf ⟨font mode⟩

       ⟨font mode⟩ must be one of the following three types:

             Em | -emphasis  Same  as  if the ‘.Em’ macro was used for the en‐
                             tire block of text.
             Li | -literal   Same as if the ‘.Li’ macro was used for  the  en‐
                             tire block of text.
             Sy | -symbolic  Same  as  if the ‘.Sy’ macro was used for the en‐
                             tire block of text.

       Both macros are neither callable nor parsed.

   Enclosure and Quoting Macros
       The concept of enclosure is similar to quoting.  The  object  being  to
       enclose one or more strings between a pair of characters like quotes or
       parentheses.   The terms quoting and enclosure are used interchangeably
       throughout this document.  Most of the one‐line enclosure macros end in
       small letter ‘q’ to give a hint of quoting, but there are a few irregu‐
       larities.  For each enclosure macro, there is a  pair  of  opening  and
       closing  macros that end with the lowercase letters ‘o’ and ‘c’ respec‐
       tively.

       Quote   Open   Close   Function                  Result
       .Aq     .Ao    .Ac     Angle Bracket Enclosure   <string>
       .Bq     .Bo    .Bc     Bracket Enclosure         [string]
       .Brq    .Bro   .Brc    Brace Enclosure           {string}
       .Dq     .Do    .Dc     Double Quote              “string”
       .Eq     .Eo    .Ec     Enclose String (in XY)    XstringY
       .Pq     .Po    .Pc     Parenthesis Enclosure     (string)
       .Ql                    Quoted Literal            “string” or string
       .Qq     .Qo    .Qc     Straight Double Quote     "string"
       .Sq     .So    .Sc     Single Quote              ‘string’

       All macros ending with ‘q’ and ‘o’ have a default width value of 12n.

       .Eo, .Ec  These macros expect the first argument to be the opening  and
                 closing strings, respectively.

       .Es, .En  To  work around the nine‐argument limit in the original troff
                 program, mdoc supports two other macros that  are  now  obso‐
                 lete.   ‘.Es’ uses its first and second parameters as opening
                 and closing marks which are then used to  enclose  the  argu‐
                 ments  of  ‘.En’.   The  default  width value is 12n for both
                 macros.

       .Eq       The first and second arguments of this macro are the  opening
                 and  closing  strings respectively, followed by the arguments
                 to be enclosed.

       .Ql       The quoted literal macro behaves  differently  in  troff  and
                 nroff modes.  If formatted with nroff(1), a quoted literal is
                 always  quoted.   If  formatted  with  troff, an item is only
                 quoted if the width of the item is less than three  constant‐
                 width characters.  This is to make short strings more visible
                 where the font change to literal (constant‐width) is less no‐
                 ticeable.

                 The default width is 16n.

       .Pf       The  prefix macro suppresses the whitespace between its first
                 and second argument:

                       .Pf ( Fa name2  (name2

                 The default width is 12n.

                 The ‘.Ns’ macro (see below)  performs  the  analogous  suffix
                 function.

       .Ap       The  ‘.Ap’  macro inserts an apostrophe and exits any special
                 text modes, continuing in ‘.No’ mode.

       Examples of quoting:

             .Aq                      ⟨⟩
             .Aq Pa ctype.h ) ,       ⟨ctype.h⟩),
             .Bq                      []
             .Bq Em Greek , French .  [Greek, French].
             .Dq                      “”
             .Dq string abc .         “string abc”.
             .Dq '\[ha][A-Z]'         “’^[A‐Z]’”
             .Ql man mdoc             ‘man mdoc’
             .Qq                      ""
             .Qq string ) ,           "string"),
             .Qq string Ns ),         "string),"
             .Sq                      ‘’
             .Sq string               ‘string’
             .Em or Ap ing            or’ing

       For a good example of nested enclosure macros,  see  the  ‘.Op’  option
       macro.   It  was  created  from the same underlying enclosure macros as
       those presented in the list above.  The ‘.Xo’ and ‘.Xc’ extended  argu‐
       ment list macros are discussed below.

   Normal text macro
       ‘No’ formats subsequent argument(s) normally, ending the effect of ‘Em’
       and  similar.  Parsing is not suppressed, so you must prefix words like
       ‘No’ with ‘\&’ to avoid their interpretation as mdoc macros.

             Usage: .No argument ...

                      .Em Use caution No here .  → Use caution here.
                      .Em No dogs allowed .      → No dogs allowed.
                      .Em \&No dogs allowed .    → No dogs allowed.

       The default width is 12n.

   No‐Space Macro
       The ‘.Ns’ macro suppresses insertion of a space between the current po‐
       sition and its first parameter.  For example,  it  is  useful  for  old
       style argument lists where there is no space between the flag and argu‐
       ment:

             Usage: ... ⟨argument⟩ Ns [⟨argument⟩] ...
                    .Ns ⟨argument⟩ ...

                      .Op Fl I Ns Ar directory  [-Idirectory]

       Note:  The ‘.Ns’ macro always invokes the ‘.No’ macro after eliminating
       the space unless another macro name follows it.  If used as  a  command
       (i.e.,  the  second form above in the ‘Usage’ line), ‘.Ns’ is identical
       to ‘.No’.

   (Sub)section cross references
       Use the ‘.Sx’ macro to cite a (sub)section  heading  within  the  given
       document.

             Usage: .Sx ⟨section‐reference⟩ ...

                      .Sx Files  → “Files”

       The default width is 16n.

   Symbolics
       The symbolic emphasis macro is generally a boldface macro in either the
       symbolic sense or the traditional English usage.

             Usage: .Sy ⟨symbol⟩ ...

                      .Sy Important Notice  → Important Notice

       The default width is 6n.

   Mathematical Symbols
       Use this macro for mathematical symbols and similar things.

             Usage: .Ms ⟨math symbol⟩ ...

                      .Ms sigma  → sigma

       The default width is 6n.

   References and Citations
       The  following  macros  make a modest attempt to handle references.  At
       best, the macros make it convenient to manually drop  in  a  subset  of
       refer(1) style references.

             .Rs     Reference  start (does not take arguments).  In a section
                     titled “See also”, it causes a break and  begins  collec‐
                     tion  of  reference  information  until the reference end
                     macro is read.
             .Re     Reference end (does not take arguments).   The  reference
                     is printed.
             .%A     Reference author name; one name per invocation.
             .%B     Book title.
             .%C     City/place.
             .%D     Date.
             .%I     Issuer/publisher name.
             .%J     Journal name.
             .%N     Issue number.
             .%O     Optional information.
             .%P     Page number.
             .%Q     Corporate or foreign author.
             .%R     Report name.
             .%T     Title of article.
             .%U     Optional hypertext reference.
             .%V     Volume.

       Macros  beginning  with  ‘%’ are not callable but accept multiple argu‐
       ments in the usual way.  Only the ‘.Tn’ macro is handled properly as  a
       parameter; other macros will cause strange output.  ‘.%B’ and ‘.%T’ can
       be used outside of the ‘.Rs/.Re’ environment.

       Example:

             .Rs
             .%A "Matthew Bar"
             .%A "John Foo"
             .%T "Implementation Notes on foobar(1)"
             .%R "Technical Report ABC-DE-12-345"
             .%Q "Drofnats College"
             .%C "Nowhere"
             .%D "April 1991"
             .Re

       produces

             Matthew Bar and John Foo, Implementation Notes on foobar(1),
             Technical Report ABC‐DE‐12‐345, Drofnats College, Nowhere, April
             1991.

   Trade Names or Acronyms
       The  trade  name macro prints its arguments at a smaller type size.  It
       is intended to  imitate  a  small  caps  fonts  for  fully  capitalized
       acronyms.

             Usage: .Tn ⟨symbol⟩ ...

                      .Tn DEC    DEC
                      .Tn ASCII  ASCII

       The default width is 10n.

   Extended Arguments
       The  .Xo and .Xc macros allow one to extend an argument list on a macro
       boundary for the ‘.It’ macro (see below).  Note that .Xo  and  .Xc  are
       implemented similarly to all other macros opening and closing an enclo‐
       sure  (without  inserting  characters, of course).  This means that the
       following is true for those macros also.

       Here is an example of ‘.Xo’ using the space mode macro to turn  spacing
       off:

             .Bd -literal -offset indent
             .Sm off
             .It Xo Sy I Ar operation
             .No \en Ar count No \en
             .Xc
             .Sm on
             .Ed

       produces

             Ioperation\ncount\n

       Another one:

             .Bd -literal -offset indent
             .Sm off
             .It Cm S No / Ar old_pattern Xo
             .No / Ar new_pattern
             .No / Op Cm g
             .Xc
             .Sm on
             .Ed

       produces

             S/old_pattern/new_pattern/[g]

       Another  example  of  ‘.Xo’  and  enclosure macros: Test the value of a
       variable.

             .Bd -literal -offset indent
             .It Xo
             .Ic .ifndef
             .Oo \&! Oc Ns Ar variable Oo
             .Ar operator variable No ...
             .Oc Xc
             .Ed

       produces

             .ifndef [!]variable [operator variable ...]

Page structure domain
   Section headings
       The following ‘.Sh’ section heading macros are required  in  every  man
       page.  The remaining section headings are recommended at the discretion
       of  the  author writing the manual page.  The ‘.Sh’ macro is parsed but
       not generally callable.  It can be used as an argument  in  a  call  to
       ‘.Sh’ only; it then reactivates the default font for ‘.Sh’.

       The default width is 8n.

       .Sh Name           The  ‘.Sh  Name’  macro is mandatory.  If not speci‐
                          fied, headers, footers,  and  page  layout  defaults
                          will  not  be set and things will be rather unpleas‐
                          ant.  The Name section consists of  at  least  three
                          items.  The first is the ‘.Nm’ name macro naming the
                          subject of the man page.  The second is the name de‐
                          scription  macro, ‘.Nd’, which separates the subject
                          name from the third item, which is the  description.
                          The  description  should be the most terse and lucid
                          possible, as the space available is small.

                          ‘.Nd’ first prints ‘-’, then all its arguments.

       .Sh Library        This section is for section two and  three  function
                          calls.   It  should  consist of a single ‘.Lb’ macro
                          call; see “Library Names”.

       .Sh Synopsis       The “Synopsis” section describes the  typical  usage
                          of  the  subject of a man page.  The macros required
                          are either ‘.Nm’,  ‘.Cd’,  or  ‘.Fn’  (and  possibly
                          ‘.Fo’,  ‘.Fc’, ‘.Fd’, and ‘.Ft’).  The function name
                          macro ‘.Fn’ is required for manual page  sections  2
                          and  3;  the command and general name macro ‘.Nm’ is
                          required for sections 1, 5, 6, 7, and 8.  Section  4
                          manuals require a ‘.Nm’, ‘.Fd’ or a ‘.Cd’ configura‐
                          tion  device  usage macro.  Several other macros may
                          be necessary to produce the synopsis line  as  shown
                          below:

                                cat [-benstuv] [-] file ...

                          The following macros were used:

                                .Nm cat
                                .Op Fl benstuv
                                .Op Fl
                                .Ar file No ...

       .Sh Description    In  most  cases  the first text in the “Description”
                          section is a brief paragraph on the  command,  func‐
                          tion  or file, followed by a lexical list of options
                          and respective explanations.  To create such a list,
                          the ‘.Bl’ (begin list), ‘.It’ (list item) and  ‘.El’
                          (end  list) macros are used (see “Lists and Columns”
                          below).

       .Sh Implementation notes
                          Implementation specific information should be placed
                          here.

       .Sh Return values  Sections 2, 3 and 9 function return values should go
                          here.  The ‘.Rv’ macro may be used to generate  text
                          for use in the “Return values” section for most sec‐
                          tion 2 and 3 library functions; see “Return Values”.

       The  following  ‘.Sh’ section headings are part of the preferred manual
       page layout and must be used  appropriately  to  maintain  consistency.
       They are listed in the order in which they would be used.

       .Sh Environment    The  Environment  section  should reveal any related
                          environment variables and clues  to  their  behavior
                          and/or usage.

       .Sh Files          Files which are used or created by the man page sub‐
                          ject  should  be  listed  via the ‘.Pa’ macro in the
                          “Files” section.

       .Sh Examples       There are several ways to create examples.  See sub‐
                          section “Examples and Displays” below for details.

       .Sh Diagnostics    Diagnostic messages from a command should be  placed
                          in  this  section.   The  ‘.Ex’ macro may be used to
                          generate text for use in the  “Diagnostics”  section
                          for  most  section  1,  6  and 8 commands; see “Exit
                          Status”.

       .Sh Compatibility  Known compatibility issues (e.g. deprecated  options
                          or parameters) should be listed here.

       .Sh Errors         Specific  error  handling,  especially  from library
                          functions (man page sections 2, 3, and 9) should  go
                          here.   The  ‘.Er’ macro is used to specify an error
                          (errno).

       .Sh See also       References to other material on the man  page  topic
                          and  cross  references  to  other relevant man pages
                          should be placed in the “See also”  section.   Cross
                          references  are  specified  using  the  ‘.Xr’ macro.
                          Currently refer(1) style references are not accommo‐
                          dated.

                          It is  recommended  that  the  cross  references  be
                          sorted  by  section  number,  then alphabetically by
                          name within each section, then separated by  commas.
                          Example:

                          ls(1), ps(1), group(5), passwd(5)

       .Sh Standards      If the command, library function, or file adheres to
                          a  specific  implementation  such as IEEE Std 1003.2
                          (“POSIX.2”) or ANSI X3.159‐1989  (“ANSI  C89”)  this
                          should  be  noted here.  If the command does not ad‐
                          here to any standard, its history should be noted in
                          the History section.

       .Sh History        Any command which does not adhere  to  any  specific
                          standards  should  be  outlined historically in this
                          section.

       .Sh Authors        Credits should be placed here.  Use the ‘.An’  macro
                          for  names  and  the ‘.Aq’ macro for email addresses
                          within optional contact information.  Explicitly in‐
                          dicate whether the person authored the initial  man‐
                          ual  page  or the software or whatever the person is
                          being credited for.

       .Sh Bugs           Blatant problems with the topic go here.

       User‐specified ‘.Sh’ sections may be added; for example,  this  section
       was set with:

                      .Sh "Page structure domain"

   Subsection headings
       Subsection  headings  have exactly the same syntax as section headings:
       ‘.Ss’ is parsed but not generally callable.  It can be used as an argu‐
       ment in a call to ‘.Ss’ only; it then reactivates the default font  for
       ‘.Ss’.

       The default width is 8n.

   Paragraphs and Line Spacing
       .Pp  The  ‘.Pp’  paragraph  command may be used to specify a line space
            where necessary.  The macro is not  necessary  after  a  ‘.Sh’  or
            ‘.Ss’  macro or before a ‘.Bl’ or ‘.Bd’ macro (which both assert a
            vertical distance unless the -compact flag is given).

            The macro is neither callable nor parsed and takes  no  arguments;
            an alternative name is ‘.Lp’.

   Keeps
       The  only  keep  that  is  implemented  at this time is for words.  The
       macros are ‘.Bk’ (begin keep) and ‘.Ek’ (end keep).   The  only  option
       that  ‘.Bk’  currently  accepts is -words (also the default); this pre‐
       vents breaks in the middle of options.  In the example  for  make  com‐
       mand‐line  arguments  (see “What’s in a Name”), the keep prevents nroff
       from placing the flag and the argument on separate lines.

       Neither macro is callable or parsed.

       More work needs to be done on the keep macros;  specifically,  a  -line
       option should be added.

   Examples and Displays
       There are seven types of displays.

       .D1  (This  is  D‐one.)  Display one line of indented text.  This macro
            is parsed but not callable.

                  -ldghfstru

            The above was produced by: .D1 Fl ldghfstru.

       .Dl  (This is D‐ell.)  Display one line of indented literal text.   The
            ‘.Dl’ example macro has been used throughout this file.  It allows
            the  indentation  (display) of one line of text.  Its default font
            is set to constant width  (literal).   ‘.Dl’  is  parsed  but  not
            callable.

                  % ls -ldg /usr/local/bin

            The above was produced by: .Dl % ls \-ldg /usr/local/bin.

       .Bd  Begin  display.   The  ‘.Bd’  display must be ended with the ‘.Ed’
            macro.  It has the following syntax:

                  .Bd {-literal | -filled | -unfilled | -ragged | -centered}
                       [-offset ⟨string⟩] [-file ⟨file name⟩] [-compact]

            -ragged            Fill, but do not adjust the right margin  (only
                               left‐justify).
            -centered          Center lines between the current left and right
                               margin.   Note  that  each  single line is cen‐
                               tered.
            -unfilled          Do not fill;  break  lines  where  their  input
                               lines  are  broken.   This can produce overlong
                               lines without warning messages.
            -filled            Display a filled block.  The block of  text  is
                               formatted  (i.e., the text is justified on both
                               the left and right side).
            -literal           Display block with literal font (usually fixed‐
                               width).   Useful  for  source  code  or  simple
                               tabbed or spaced text.
            -file ⟨file name⟩  The  file  whose name follows the -file flag is
                               read and displayed  before  any  data  enclosed
                               with  ‘.Bd’  and ‘.Ed’, using the selected dis‐
                               play type.  Any troff/mdoc commands in the file
                               will be processed.
            -offset ⟨string⟩   If -offset is specified with one of the follow‐
                               ing strings, the string is interpreted to indi‐
                               cate the level of indentation for the forthcom‐
                               ing block of text:

                               left        Align block  on  the  current  left
                                           margin; this is the default mode of
                                           ‘.Bd’.
                               center      Supposedly  center  the  block.  At
                                           this time unfortunately, the  block
                                           merely  gets  left aligned about an
                                           imaginary center margin.
                               indent      Indent by one default indent  value
                                           or  tab.   The default indent value
                                           is also  used  for  the  ‘.D1’  and
                                           ‘.Dl’  macros, so one is guaranteed
                                           the two types of displays will line
                                           up.  The indentation value is  nor‐
                                           mally set to 6n or about two thirds
                                           of  an  inch  (six  constant  width
                                           characters).
                               indent-two  Indent two times the default indent
                                           value.
                               right       This left aligns  the  block  about
                                           two  inches  from the right side of
                                           the page.  This  macro  needs  work
                                           and  perhaps may never do the right
                                           thing within troff.

                               If ⟨string⟩ is a valid numeric  expression  in‐
                               stead  (with  a  scaling  indicator  other than
                               ‘u’), use that value for indentation.  The most
                               useful scaling  indicators  are  ‘m’  and  ‘n’,
                               specifying  the  so‐called  Em  and  En square.
                               This is approximately the width of the  letters
                               ‘m’  and  ‘n’  respectively of the current font
                               (for nroff output, both scaling indicators give
                               the same values).  If ⟨string⟩ isn’t a  numeric
                               expression,  it is tested whether it is an mdoc
                               macro name, and the default offset value  asso‐
                               ciated  with  this  macro is used.  Finally, if
                               all tests fail, the width of ⟨string⟩  (typeset
                               with  a  fixed‐width font) is taken as the off‐
                               set.
            -compact           Suppress insertion of vertical space before be‐
                               gin of display.

       .Ed  End display (takes no arguments).

   Lists and Columns
       There are several types of lists which may be initiated with the  ‘.Bl’
       begin‐list  macro.   Items within the list are specified with the ‘.It’
       item macro, and each list must end with the ‘.El’ macro.  Lists may  be
       nested  within  themselves and within displays.  The use of columns in‐
       side of lists or lists inside of columns is untested.

       In addition, several list attributes may be specified such as the width
       of a tag, the list offset, and compactness (blank lines  between  items
       allowed  or disallowed).  Most of this document has been formatted with
       a tag style list (-tag).

       It has the following syntax forms:

             .Bl {-hang | -ohang | -tag | -diag | -inset} [-width ⟨string⟩]
                  [-offset ⟨string⟩] [-compact]
             .Bl -column [-offset ⟨string⟩] ⟨string1⟩ ⟨string2⟩ ...
             .Bl {-item | -enum [-nested] | -bullet | -hyphen | -dash}
                  [-offset ⟨string⟩] [-compact]

       And now a detailed description of the list types.

       -bullet  A bullet list.

                      .Bl -bullet -offset indent -compact
                      .It
                      Bullet one goes here.
                      .It
                      Bullet two here.
                      .El

                Produces:

                      •   Bullet one goes here.
                      •   Bullet two here.

       -dash (or -hyphen)
                A dash list.

                      .Bl -dash -offset indent -compact
                      .It
                      Dash one goes here.
                      .It
                      Dash two here.
                      .El

                Produces:

                      -   Dash one goes here.
                      -   Dash two here.

       -enum    An enumerated list.

                      .Bl -enum -offset indent -compact
                      .It
                      Item one goes here.
                      .It
                      And item two here.
                      .El

                The result:

                      1.   Item one goes here.
                      2.   And item two here.

                If you want to nest enumerated lists,  use  the  -nested  flag
                (starting with the second‐level list):

                      .Bl -enum -offset indent -compact
                      .It
                      Item one goes here
                      .Bl -enum -nested -compact
                      .It
                      Item two goes here.
                      .It
                      And item three here.
                      .El
                      .It
                      And item four here.
                      .El

                Result:

                      1.   Item one goes here.
                           1.1.   Item two goes here.
                           1.2.   And item three here.
                      2.   And item four here.

       -item    A list of type -item without list markers.

                      .Bl -item -offset indent
                      .It
                      Item one goes here.
                      Item one goes here.
                      Item one goes here.
                      .It
                      Item two here.
                      Item two here.
                      Item two here.
                      .El

                Produces:

                      Item  one goes here.  Item one goes here.  Item one goes
                      here.

                      Item two here.  Item two here.  Item two here.

       -tag     A list with tags.  Use -width to specify the tag width.

                      SL    sleep time of the process (seconds blocked)
                      PAGEIN
                            number of disk I/O operations resulting from  ref‐
                            erences  by  the  process  to  pages not loaded in
                            core.
                      UID   numerical user‐id of process owner
                      PPID  numerical id of parent of process  priority  (non‐
                            positive when in non‐interruptible wait)

                The raw text:

                      .Bl -tag -width "PPID" -compact -offset indent
                      .It SL
                      sleep time of the process (seconds blocked)
                      .It PAGEIN
                      number of disk I/O operations resulting from references
                      by the process to pages not loaded in core.
                      .It UID
                      numerical user-id of process owner
                      .It PPID
                      numerical id of parent of process priority
                      (non-positive when in non-interruptible wait)
                      .El

       -diag    Diag  lists create section four diagnostic lists and are simi‐
                lar to inset lists except callable macros  are  ignored.   The
                -width flag is not meaningful in this context.

                Example:

                      .Bl -diag
                      .It You can’t use Sy here.
                      The message says all.
                      .El

                produces

                You can’t use Sy here.  The message says all.

       -hang    A list with hanging tags.

                      Hanged  labels  appear  similar to tagged lists when the
                              label is smaller than the label width.

                      Longer hanged list labels blend into the  paragraph  un‐
                              like tagged paragraph labels.

                And the unformatted text which created it:

                      .Bl -hang -offset indent
                      .It Em Hanged
                      labels appear similar to tagged lists when the
                      label is smaller than the label width.
                      .It Em Longer hanged list labels
                      blend into the paragraph unlike
                      tagged paragraph labels.
                      .El

       -ohang   Lists  with  overhanging  tags  do not use indentation for the
                items; tags are written to a separate line.

                      SL
                      sleep time of the process (seconds blocked)

                      PAGEIN
                      number of disk I/O operations resulting from  references
                      by the process to pages not loaded in core.

                      UID
                      numerical user‐id of process owner

                      PPID
                      numerical id of parent of process priority (non‐positive
                      when in non‐interruptible wait)

                The raw text:

                      .Bl -ohang -offset indent
                      .It Sy SL
                      sleep time of the process (seconds blocked)
                      .It Sy PAGEIN
                      number of disk I/O operations resulting from references
                      by the process to pages not loaded in core.
                      .It Sy UID
                      numerical user-id of process owner
                      .It Sy PPID
                      numerical id of parent of process priority
                      (non-positive when in non-interruptible wait)
                      .El

       -inset   Here is an example of inset labels:

                      Tag  The tagged list (also called a tagged paragraph) is
                      the most common type of list used in the Berkeley  manu‐
                      als.  Use a -width attribute as described below.

                      Diag Diag lists create section four diagnostic lists and
                      are  similar  to  inset lists except callable macros are
                      ignored.

                      Hang Hanged labels are a matter of taste.

                      Ohang Overhanging labels are nice  when  space  is  con‐
                      strained.

                      Inset  Inset labels are useful for controlling blocks of
                      paragraphs and are valuable for converting mdoc  manuals
                      to other formats.

                Here is the source text which produced the above example:

                      .Bl -inset -offset indent
                      .It Em Tag
                      The tagged list (also called a tagged paragraph)
                      is the most common type of list used in the
                      Berkeley manuals.
                      .It Em Diag
                      Diag lists create section four diagnostic lists
                      and are similar to inset lists except callable
                      macros are ignored.
                      .It Em Hang
                      Hanged labels are a matter of taste.
                      .It Em Ohang
                      Overhanging labels are nice when space is constrained.
                      .It Em Inset
                      Inset labels are useful for controlling blocks of
                      paragraphs and are valuable for converting
                      .Xr mdoc
                      manuals to other formats.
                      .El

       -column  This  list  type  generates  multiple  columns.  The number of
                columns and the width of each column is determined by the  ar‐
                guments  to  the  -column list, ⟨string1⟩, ⟨string2⟩, etc.  If
                ⟨stringN⟩ starts with a ‘.’ (dot) immediately  followed  by  a
                valid  mdoc  macro name, interpret ⟨stringN⟩ and use the width
                of the result.  Otherwise, the  width  of  ⟨stringN⟩  (typeset
                with a fixed‐width font) is taken as the Nth column width.

                Each  ‘.It’  argument  is  parsed  to  make a row, each column
                within the row is a separate argument separated by  a  tab  or
                the ‘.Ta’ macro.

                The table:

                      String    Nroff    Troff
                      <=        <=       ≤
                      >=        >=       ≥

                was produced by:

                .Bl -column -offset indent ".Sy String" ".Sy Nroff" ".Sy Troff"
                .It Sy String Ta Sy Nroff Ta Sy Troff
                .It Li <= Ta <= Ta \*(<=
                .It Li >= Ta >= Ta \*(>=
                .El

                Don’t  abuse  this  list  type!  For more complicated cases it
                might be far better and easier to use tbl(1), the  table  pre‐
                processor.

       Other keywords:

       -width ⟨string⟩   If  ⟨string⟩ starts with a ‘.’ (dot) immediately fol‐
                         lowed by a valid mdoc macro name, interpret  ⟨string⟩
                         and use the width of the result.  Almost all lists in
                         this document use this option.

                         Example:

                               .Bl -tag -width ".Fl test Ao Ar string Ac"
                               .It Fl test Ao Ar string Ac
                               This is a longer sentence to show how the
                               .Fl width
                               flag works in combination with a tag list.
                               .El

                         gives:

                         -test ⟨string⟩  This is a longer sentence to show how
                                         the  -width flag works in combination
                                         with a tag list.

                         (Note that the current state of mdoc is saved  before
                         ⟨string⟩  is  interpreted;  afterwards, all variables
                         are restored again.  However, boxes (used for  enclo‐
                         sures)  can’t  be  saved in GNU troff(1); as a conse‐
                         quence, arguments must always be  balanced  to  avoid
                         nasty  errors.   For  example,  do  not write ‘.Ao Ar
                         string’ but ‘.Ao Ar string Xc’ instead if you  really
                         need only an opening angle bracket.)

                         Otherwise,  if ⟨string⟩ is a valid numeric expression
                         (with a scaling indicator other than ‘u’),  use  that
                         value for indentation.  The most useful scaling indi‐
                         cators  are  ‘m’ and ‘n’, specifying the so‐called Em
                         and En square.  This is approximately  the  width  of
                         the  letters  ‘m’ and ‘n’ respectively of the current
                         font (for nroff output, both scaling indicators  give
                         the  same  values).   If ⟨string⟩ isn’t a numeric ex‐
                         pression, it is tested whether it is  an  mdoc  macro
                         name,  and  the  default  width value associated with
                         this macro is used.  Finally, if all tests fail,  the
                         width  of  ⟨string⟩ (typeset with a fixed‐width font)
                         is taken as the width.

                         If a width is not specified for the  tag  list  type,
                         ‘6n’ is used.

       -offset ⟨string⟩  If  ⟨string⟩  is indent, a default indent value (nor‐
                         mally set to 6n, similar to the value used  in  ‘.Dl’
                         or  ‘.Bd’)  is  used.  If ⟨string⟩ is a valid numeric
                         expression instead (with a  scaling  indicator  other
                         than  ‘u’), use that value for indentation.  The most
                         useful scaling indicators are ‘m’ and ‘n’, specifying
                         the so‐called Em and En  square.   This  is  approxi‐
                         mately  the  width of the letters ‘m’ and ‘n’ respec‐
                         tively of the current font (for  nroff  output,  both
                         scaling   indicators   give  the  same  values).   If
                         ⟨string⟩ isn’t a numeric  expression,  it  is  tested
                         whether  it  is  an  mdoc macro name, and the default
                         offset value associated with this macro is used.  Fi‐
                         nally, if all  tests  fail,  the  width  of  ⟨string⟩
                         (typeset  with  a  fixed‐width  font) is taken as the
                         offset.

       -compact          Suppress insertion of vertical space before the  list
                         and between list items.

Miscellaneous macros
       A double handful of macros fit only uncomfortably into one of the above
       sections.   Of  these,  we  couldn’t find attested examples for ‘Me’ or
       ‘Ot’.  They are documented here  for  completeness—if  you  know  their
       proper  usage, please send a mail to groff@gnu.org and include a speci‐
       men with its provenance.

       .Bt  formats boilerplate text.

                  .Bt  → is currently in beta test.

            It is neither callable nor parsed and takes no arguments.  Its de‐
            fault width is 6n.

       .Fr  is an obsolete means of specifying a function return value.

                  Usage: .Fr return‐value ...

            ‘Fr’ allows a break right before the return value (usually a  sin‐
            gle digit) which is bad typographical behaviour.  Instead, set the
            return  value with the rest of the code, using ‘\~’ to tie the re‐
            turn value to the previous word.

            Its default width is 12n.

       .Hf  Inlines the contents of a (header) file into the document.

                  Usage: .Hf file

            It first prints ‘File:’ followed by the file name, then  the  con‐
            tents of file.  It is neither callable nor parsed.

       .Lk  Embed hyperlink.

                  Usage: .Lk uri [link‐text]

            Its default width is 6n.

       .Me  Usage  unknown.  The mdoc sources describe it as a macro for “menu
            entries”.

            Its default width is 6n.

       .Mt  Embed email address.

                  Usage: .Mt email‐address

            Its default width is 6n.

       .Ot  Usage unknown.  The mdoc sources describe it as “old function type
            (fortran)”.

       .Sm  Manipulate or toggle argument‐spacing mode.

                  Usage: .Sm [on | off] ...

            If argument‐spacing mode is off, no spaces between macro arguments
            are inserted.  If called without a parameter (or if the next para‐
            meter is neither ‘on’ nor ‘off’),  ‘Sm’  toggles  argument‐spacing
            mode.

            Its default width is 8n.

       .Ud  formats boilerplate text.

                  .Ud  → currently under development.

            It is neither callable nor parsed and takes no arguments.  Its de‐
            fault width is 8n.

Predefined strings
       The following strings are predefined for compatibility with legacy mdoc
       documents.   Contemporary ones should use the alternatives shown in the
       “Prefer” column below.  See groff_char(7)  for  a  full  discussion  of
       these special character escape sequences.

       String   7‐bit     8‐bit     UCS   Prefer   Meaning
       \*(<=    <=        <=        ≤     \(<=     less than or equal to
       \*(>=    >=        >=        ≥     \(>=     greater than or equal to
       \*(Rq    "         "         ”     \(rq     right double quote
       \*(Lq    "         "         “     \(lq     left double quote
       \*(ua    ^         ^         ↑     \(ua     vertical arrow up
       \*(aa    '         ´         ´     \(aa     acute accent
       \*(ga    `         `         `     \(ga     grave accent
       \*(q     "         "         "     \(dq     neutral double quote
       \*(Pi    pi        pi        π     \(*p     lowercase pi
       \*(Ne    !=        !=        ≠     \(!=     not equals
       \*(Le    <=        <=        ≤     \(<=     less than or equal to
       \*(Ge    >=        >=        ≥     \(>=     greater than or equal to
       \*(Lt    <         <         <     <        less than
       \*(Gt    >         >         >     >        greater than
       \*(Pm    +-        ±         ±     \(+-     plus or minus
       \*(If    infinity  infinity  ∞     \(if     infinity
       \*(Am    &         &         &     &        ampersand
       \*(Na    NaN       NaN       NaN   NaN      not a number
       \*(Ba    |         |         |     |        bar

       Some  column  headings  are shorthand for standardized character encod‐
       ings; “7‐bit” for ISO 646:1991 IRV (US‐ASCII), “8‐bit” for  ISO  8859‐1
       (Latin‐1)  and  IBM  code  page  1047, and “UCS” for ISO 10646 (Unicode
       character set).  Historically, mdoc configured the  string  definitions
       to fit the capabilities expected of the output device.  Old typesetters
       lacked directional double quotes, producing repeated directional single
       quotes  ‘‘like  this’’; early versions of mdoc in fact defined the ‘Lq’
       and ‘Rq’ strings this way.  Nowadays, output drivers take  on  the  re‐
       sponsibility  of glyph substitution, as they possess relevant knowledge
       of their available repertoires.

Diagnostics
       The debugging macro ‘.Db’ offered by previous versions of mdoc  is  un‐
       available  in  GNU troff(1) since the latter provides better facilities
       to check parameters; additionally, groff mdoc implements many error and
       warning messages, making the package more robust and more verbose.

       The remaining debugging macro  is  ‘.Rd’,  which  dumps  the  package’s
       global  register  and  string contents to the standard error stream.  A
       normal user will never need it.

Options
       The following groff options set registers (with -r) and  strings  (with
       -d) recognized and used by the mdoc macro package.  To ensure rendering
       consistent  with output device capabilities and reader preferences, man
       pages should never manipulate them.

       Setting string ‘AD’ configures the adjustment mode for  most  formatted
       text.   Typical  values are ‘b’ for adjustment to both margins (the de‐
       fault), or ‘l’ for left alignment (ragged right margin).  Any valid ar‐
       gument to groff’s ‘ad’ request may be used.  See groff(7) for less‐com‐
       mon choices.
             groff -Tutf8 -dAD=l -mdoc groff_mdoc.7 | less -R

       Setting register ‘C’ to 1 numbers output  pages  consecutively,  rather
       than resetting the page number to 1 (or the value of register ‘P’) with
       each new mdoc document.

       By  default,  the package inhibits page breaks, headers, and footers in
       the midst of the document text if it is being displayed with a terminal
       device such as ‘latin1’ or ‘utf8’, to enable more efficient viewing  of
       the  page.   This  behavior can be changed to format the page as if for
       66‐line Teletype output by setting the  continuous  rendering  register
       ‘cR’ to zero while calling groff(1).
             groff -Tlatin1 -rcR=0 -mdoc foo.man > foo.txt
       On HTML devices, it cannot be disabled.

       Section  headings  (defined with ‘.Sh’) and page titles in headers (de‐
       fined with ‘.Dt’) can be presented in full capitals by setting the reg‐
       isters ‘CS’ and ‘CT’, respectively, to 1.   These  transformations  are
       off by default because they discard case distinction information.

       Setting  register  ‘D’  to 1 enables double‐sided page layout, which is
       only distinct when not continuously rendering.  It places the page num‐
       ber at the bottom right on odd‐numbered (recto) pages, and at the  bot‐
       tom left on even‐numbered (verso) pages, swapping places with the argu‐
       ments to ‘.Os’.
             groff -Tps -rD1 -mdoc foo.man > foo.ps

       The  value  of  the ‘FT’ register determines the footer’s distance from
       the page bottom; this amount is always negative and  should  specify  a
       scaling  unit.   At one half‐inch above this location, the page text is
       broken before writing the footer.  It is ignored if continuous  render‐
       ing is enabled.  The default is -0.5i.

       The ‘HF’ string sets the font used for section and subsection headings;
       the default is ‘B’ (bold style of the default family).  Any valid argu‐
       ment to groff’s ‘ft’ request may be used.

       Normally,  automatic hyphenation is enabled using a mode appropriate to
       the groff locale; see section “Localization“ of groff(7).   It  can  be
       disabled by setting the ‘HY’ register to zero.
             groff -Tutf8 -rHY=0 -mdoc foo.man | less -R

       The paragraph and subsection heading indentation amounts can be changed
       by setting the registers ‘IN’ and ‘SN’.
             groff -Tutf8 -rIN=5n -rSN=2n -mdoc foo.man | less -R
       The default paragraph indentation is 7.2n on typesetters and 7n on ter‐
       minals.   The default subsection heading indentation amount is 3n; sec‐
       tion headings are set with an indentation of zero.

       The line and title lengths can be changed by setting the registers ‘LL’
       and ‘LT’, respectively:
             groff -Tutf8 -rLL=100n -rLT=100n -mdoc foo.man | less -R
       If not set, both registers default to 78n for terminal devices and 6.5i
       otherwise.

       Setting the ‘P’ register starts enumeration of pages at its value.  The
       default is 1.

       To change the document font size to 11p or 12p, set  register  ‘S’  ac‐
       cordingly:
             groff -Tdvi -rS11 -mdoc foo.man > foo.dvi
       Register ‘S’ is ignored when formatting for terminal devices.

       Setting  the  ‘X’ register to a page number p numbers its successors as
       pa, pb, pc, and so forth.  The register tracking the suffixed page let‐
       ter uses format ‘a’ (see the ‘af’ request in groff(7)).

Files
       /usr/share/groff/1.23.0/tmac/andoc.tmac
               This brief groff program detects whether the man or mdoc  macro
               package is being used by a document and loads the correct macro
               definitions, taking advantage of the fact that pages using them
               must  call  TH or Dd, respectively, before any other macros.  A
               user typing, for example,
                     groff -mandoc page.1
               need not know which package the file page.1 uses.  Multiple man
               pages, in either format, can  be  handled;  andoc.tmac  reloads
               each macro package as necessary.

       /usr/share/groff/1.23.0/tmac/doc.tmac
               implements the bulk of the groff mdoc package and loads further
               components as needed from the mdoc subdirectory.

       /usr/share/groff/1.23.0/tmac/mdoc.tmac
               is a wrapper that loads doc.tmac.

       /usr/share/groff/1.23.0/tmac/mdoc/doc-common
               defines  macros, registers, and strings concerned with the pro‐
               duction of formatted output.  It includes strings of  the  form
               ‘doc-volume-ds-X’  and ‘doc-volume-as-X’ for manual section ti‐
               tles and architecture identifiers, respectively, where X is  an
               argument recognized by .Dt.

       /usr/share/groff/1.23.0/tmac/mdoc/doc-nroff
               defines  parameters  appropriate  for rendering to terminal de‐
               vices.

       /usr/share/groff/1.23.0/tmac/mdoc/doc-ditroff
               defines parameters appropriate for rendering to typesetter  de‐
               vices.

       /usr/share/groff/1.23.0/tmac/mdoc/doc-syms
               defines  many  strings  and  macros  that interpolate formatted
               text, such as names of  operating  system  releases,  *BSD  li‐
               braries,  and standards documents.  The string names are of the
               form  ‘doc-str-O-V’,  ‘doc-str-St--S-I’  (observe  the   double
               dashes),  or  ‘doc-str-Lb-L’,  where  O is one of the operating
               system macros from section “General text domain” above, V is an
               encoding of an  operating  system  release  (sometimes  omitted
               along  with  the ‘-’ preceding it), S an identifier for a stan‐
               dards body or committee, I one for an issue of a standard  pro‐
               mulgated by S, and L a keyword identifying a *BSD library.

       /usr/share/groff/site-tmac/mdoc.local
               This  file  houses  local  additions  and customizations to the
               package.  It can be empty.

See also
       The mandoc: https://mandoc.bsd.lv/ project maintains an independent im‐
       plementation of the mdoc language and a renderer that  directly  parses
       its markup as well as that of man.

       groff(1), man(1), troff(1), groff_man(7), mdoc(7)

Bugs
       Section 3f has not been added to the header routines.

       ‘.Fn’  needs  to  have  a check to prevent splitting up the line if its
       length is too short.  Occasionally it separates the  last  parenthesis,
       and sometimes looks ridiculous if output lines are being filled.

       The list and display macros do not do any keeps and certainly should be
       able to.

       As  of groff 1.23, ‘Tn’ no longer changes the type size; this function‐
       ality may return in the next release.

groff 1.23.0                      2 July 2023                    groff_mdoc(7)
───────────────────────────────────────────────────────────────────────────────
groff_me(7)            Miscellaneous Information Manual            groff_me(7)

Name
       groff_me - “me” macro package for formatting roff documents

Synopsis
       groff -me [option ...] [file ...]
       groff -m me [option ...] [file ...]

Description
       The GNU implementation of the me macro package is  part  of  the  groff
       document  formatting  system.   The me package of macro definitions for
       the roff language provides a convenient facility for preparing  techni‐
       cal  papers  in  various formats.  This version is based on the me dis‐
       tributed with 4.4BSD and can be used with the GNU  troff  formatter  as
       well as those descended from AT&T troff.

       Some  formatter  requests affect page layout unpredictably when used in
       conjunction with this package; however, the following may be used  with
       impunity  after  the  first call to a paragraphing macro like lp or pp.
       Some arguments are optional; see groff(7) for details, particularly  of
       requests whose argument list is designated with an ellipsis.  An aster‐
       isk * marks groff extensions.

       ad c       set text adjustment mode to c
       af r f     assign format f to register r
       am m e     append to macro m until e called
       as s t     append rest of line t to string s
       bp n       begin new page numbered n
       br         break output line
       ce n       center next n output lines
       cp n       en‐/disable AT&T troff compatibility mode*
       de m e     define macro m until e called
       do t       interpret input t with compatibility mode off*
       ds s t     define rest of line t as string s
       el t       interpret t if corresponding ie false
       fc c d     set field delimiter c and padding glyph d
       fi         enable filling
       hc c       set hyphenation character to c
       hy m       set automatic hyphenation mode to m
       ie p t     as if, but enable interpretation of later el
       if p t     if condition p, interpret rest of line t
       in h       set indentation to distance h
       lc c       set leader repetition glyph to c
       ls n       set line spacing to n
       mc c h     set (right) margin glyph to c at distance h
       mk r       mark vertical position in register r
       na         disable adjustment of text
       ne v       need vertical space of distance v
       nf         disable filling
       nh         disable automatic hyphenation
       nr r n i   assign register r value n with auto‐increment i
       ns         begin no‐space mode
       pl v       set page length to v
       pn n       set next page number to n
       po h       set page offset to h
       rj n       right‐align next n output lines*
       rm m       remove macro, string, or request m
       rn m n     rename macro, string, or request m to n
       rr r       remove register r
       rs         resume spacing (end no‐space mode)
       rt v       return to vertical position set by mk, or v
       so f       source (interpolate) input file f
       sp n       insert n lines of vertical space
       ta ...     set tab stops
       tc c       set tab repetition glyph to c
       ti h       set temporary indentation (next line only) to h
       tl ...     output three‐part title
       tr ...     translate characters
       ul n       underline next n output lines

       Except  on title pages (produced by calling tp), me suppresses the out‐
       put of vertical space at the tops of pages (after  the  output  of  any
       page header); the sp request will thus not work there.  You can instead
       call  bl or enclose the desired spacing request in a diversion, for in‐
       stance by calling (b and )b.  me also intercepts the  ll  request;  see
       the “me Reference Manual” for details.

   Name space
       Objects in me follow a rigid naming convention.  To avoid conflict, any
       user‐defined register, string, or macro names should be single numerals
       or  uppercase  letters,  or any longer sequence of letters and numerals
       with at least one uppercase letter.  (For portability between  BSD  and
       groff  me,  limit  names  to two characters, and avoid the name [ (left
       square bracket).)  The names  employed  by  any  preprocessors  in  use
       should also not be repurposed.

   Macros
       $0   post‐section heading hook
       $1   pre‐section depth 1 hook
       $2   pre‐section depth 2 hook
       $3   pre‐section depth 3 hook
       $4   pre‐section depth 4 hook
       $5   pre‐section depth 5 hook
       $6   pre‐section depth 6 hook
       $C   post‐chapter title hook
       $H   page/column heading hook
       $c   output chapter number and title
       $f   output footer
       $h   output header
       $p   output section heading
       $s   output footnote area separator
       (b   begin block
       (c   begin centered block
       (d   begin delayed text
       (f   begin footnote
       (l   begin list
       (q   begin long quotation
       (x   begin index entry
       (z   begin floating keep
       )b   end block
       )c   end centered block
       )d   end delayed text
       )f   end footnote
       )l   end list
       )q   end long quotation
       )x   end index entry
       )z   end floating keep
       ++   set document segment type
       +c   begin chapter
       1c   end multi‐column layout
       2c   begin multi‐column layout
       EN   end eqn equation
       EQ   begin eqn equation
       GE   end grn picture with drawing position at bottom
       GF   end grn picture with drawing position at top
       GS   start grn picture
       IE   end ideal picture with drawing position at bottom
       IF   end ideal picture with drawing position at top
       IS   start ideal picture
       PE   end pic picture with drawing position at bottom
       PF   end pic picture with drawing position at top
       PS   start pic picture
       TE   end tbl table
       TH   end heading for multi‐page tbl table
       TS   start tbl table
       b    embolden argument
       ba   set base indentation
       bc   begin new column
       bi   embolden and italicize argument
       bx   box argument
       ef   set even‐numbered page footer
       eh   set even‐numbered page header
       ep   end page
       fo   set footer
       he   set header
       hl   draw horizontal line
       hx   suppress next page’s headers/footers
       i    italicize argument
       ip   begin indented paragraph
       ld   reset localization and date registers and strings*
       ll   set line length
       lp   begin fully left‐aligned paragraph
       np   begin numbered paragraph
       of   set odd‐numbered page footer
       oh   set odd‐numbered page header
       pd   output delayed text
       pp   begin first‐line indented paragraph
       q    quote argument
       r    set argument in roman
       re   reset tab stops
       sh   begin numbered section
       sm   set argument at smaller type size
       sx   change section depth
       sz   set type size and vertical spacing
       tp   begin title page
       u    underline argument
       uh   begin unnumbered section
       xl   set line length (local)
       xp   output index

       Some macros are provided for “old” roff(1) compatibility.  The “me Ref‐
       erence Manual” describes alternatives for modern documents.

       ar   use Arabic numerals for page numbers
       bl   insert space (even at page top; cf. sp)
       ix   set indentation without break
       m1   set page top to header distance
       m2   set header to text distance
       m3   set text to footer distance
       m4   set footer to page bottom distance
       n1   begin output line numbering
       n2   end or alter output line numbering
       pa   begin page
       ro   use Roman numerals for page numbers
       sk   skip next page

   Registers
       $0   section depth
       $1   first section number component
       $2   second section number component
       $3   third section number component
       $4   fourth section number component
       $5   fifth section number component
       $6   sixth section number component
       $c   current column number
       $d   delayed text number
       $f   footnote number
       $i   paragraph base indentation
       $l   column width
       $m   number of available columns
       $p   numbered paragraph number
       $s   column spacing (indentation)
       bi   display (block) indentation
       bm   distance from text area to page bottom
       bs   display (block) pre/post space
       bt   block threshold for keeps
       ch   current chapter number
       df   display font
       dv   vertical spacing of displayed text (as percentage)*
       es   equation pre/post space
       ff   footnote font
       fi   footnote indentation (first line only)
       fm   footer margin
       fp   footnote type size in points
       fs   footnote prespace
       fu   footnote undent (right indentation)
       hm   header margin
       ii   indented paragraph indentation
       no   line numbering offset*
       pf   paragraph font
       pi   paragraph indentation
       po   page offset
       pp   paragraph type size in points
       ps   paragraph prespace
       qi   long quotation left/right indentation
       qp   long quotation type size in points
       qs   long quotation pre/post space
       sf   section title font
       si   section indentation per level of depth
       so   additional section title offset
       sp   section title type size in points
       ss   section prespace
       sx   super/subscript line height increase*
       tf   title font
       tm   distance from page top to text area
       tp   title type size in points
       tv   vertical spacing of text (as percentage)*
       xs   index entry prespace
       xu   index undent (right indentation)
       y2   year of the century*
       y4   year*
       yr   year minus 1900
       zs   floating keep pre/post space

   Strings
       #    delayed text marker
       $n   concatenated section number
       *    footnote marker
       -    em dash
       <    begin subscripting
       >    end subscripting
       dw   weekday name
       lq   left double quotation mark
       mo   month name
       rq   right double quotation mark
       td   date
       wa   term for “appendix” used by .$c*
       wc   term for “chapter” used by .$c*
       {    begin superscripting
       }    end superscripting

Files
       /usr/share/groff/1.23.0/tmac/e.tmac
              implements the package.

       /usr/share/groff/1.23.0/tmac/refer-me.tmac
              implements refer(1) support for me.

       /usr/share/groff/1.23.0/tmac/me.tmac
              is  a  wrapper  enabling the package to be loaded with “groff -m
              me”.

Notes
       Early roff macro packages often limited their names to a single letter,
       which followed the formatter’s m flag letter, resulting in mm, ms,  mv,
       mn,  and so on.  The “e” in “me” stands for “Eric P. Allman”, who wrote
       the macro package and the  original  technical  papers  documenting  it
       while an undergraduate at the University of California.

See also
       Two manuals are available in source and rendered form.  On your system,
       they may be compressed and/or available in additional formats.

       /usr/share/doc/groff-1.23.0/meintro.me
       /usr/share/doc/groff-1.23.0/meintro.ps
              is  “Writing  Papers  with  Groff Using -me”, by Eric P. Allman,
              adapted for groff by James Clark.

       /usr/share/doc/groff-1.23.0/meref.me
       /usr/share/doc/groff-1.23.0/meref.ps
              is the “me Reference Manual”, by Eric  P.  Allman,  adapted  for
              groff by James Clark and G. Branden Robinson.

       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       For   preprocessors  supported  by  me,  see  eqn(1),  grn(1),  pic(1),
       refer(1), and tbl(1).

       groff(1), troff(1), groff(7)

groff 1.23.0                      2 July 2023                      groff_me(7)
───────────────────────────────────────────────────────────────────────────────
groff_mm(7)            Miscellaneous Information Manual            groff_mm(7)

Name
       groff_mm - memorandum macros for GNU roff

Synopsis
       groff -mm [option ...] [file ...]
       groff -m mm [option ...] [file ...]

Description
       The GNU implementation of the mm macro package is  part  of  the  groff
       document  formatting system.  The mm package is suitable for the compo‐
       sition of letters, memoranda, reports, and books.

       Call an mm macro at the beginning of a document to initialize the pack‐
       age.  A simple mm document might use only P for paragraphing.  Set num‐
       bered and unnumbered section headings  with  H  and  HU,  respectively.
       Change  the  style  of the typeface with B, I, and R; you can alternate
       styles with BI, BR, IB, IR, RB, and RI.  Several  nestable  list  types
       are available via AL, BL, BVL, DL, ML, RL, and VL; each of these begins
       a  list,  to which LI adds an item and LE ends the (nested) list.  Cus‐
       tomized list arrangements are supported by LB.  DS and DF start  static
       and floating displays, respectively; either is terminated with DE.

       groff  mm is intended to be compatible with the mm implementation found
       in the AT&T Documenter’s Workbench (DWB), with  the  following  limita‐
       tions.

       • Omitted  features  include  the logo and company name strings, }Z and
         ]S, respectively; the encoded company site location addresses  recog‐
         nized  as the third argument to the AU macro; the Pv (“private” head‐
         ing) register; and the OK (other keywords), and PM (proprietary mark‐
         ings) macros.

       • The CS (output cover sheet) macro is implemented only for  memorandum
         type 4.

       • The  grap  preprocessor  is  not  explicitly  supported; no G1 and G2
         macros are defined.

       • The registers A, C, E, T, and U, typically  set  from  the  troff  or
         nroff command lines with DWB mm, are not recognized.

       • When  setting  the registers L or W from the command line, use an ex‐
         plicit scaling unit to avoid surprises.

       • DWB mm’s nP macro indented the second line of a paragraph to align it
         with the start of the text of the first (after the paragraph number);
         groff mm’s does not.

       • Cut marks are not supported.

       DWB mm supported only seven levels of heading.  As a compatible  exten‐
       sion,  groff mm supports fourteen, introducing new registers H8 through
       H14, and affecting the interpretation of the HF and HP strings.

       Macro, register, and string descriptions in this page  frequently  men‐
       tion each other; most cross references are to macros.  Where a register
       or string is referenced, its type is explicitly identified.  mm’s macro
       names  are usually in full capitals; registers and strings tend to have
       mixed‐case names.

   Document styles
       groff mm offers three different frameworks for  document  organization.
       COVER/COVEND  is a flexible means of preparing any document requiring a
       cover page.  LT/LO aids preparation of  typical  Anglophone  correspon‐
       dence  (business  letters, for example).  The MT memorandum type mecha‐
       nism implements a group of formal styles historically used by AT&T Bell
       Laboratories.  Your document can  select  at  most  one  of  these  ap‐
       proaches; when used, each disables the others.

   Localization
       groff  mm is designed to be easily localized.  For languages other than
       English, strings that can appear in output are collected  in  the  file
       /usr/share/groff/1.23.0/tmac/xx.tmac, where xx is an ISO 639 two‐letter
       language  identifier.  Localization packages should be loaded after mm;
       for example, you might format a Swedish mm document  with  the  command
       “groff -mm -msv”.

       This  package  can also be localized by site or territory; for example,
       /usr/share/groff/1.23.0/tmac/mse.tmac illustrates how to adapt the out‐
       put to a national standard using its ISO 3166 territory code.   Such  a
       package  can define a string that causes a macro file /usr/share/groff/
       1.23.0/tmac/mm/territory_locale to be loaded at package initialization.
       If this mechanism is not  used,  /usr/share/groff/1.23.0/tmac/mm/locale
       is loaded instead.  No diagnostic is produced if these files do not ex‐
       ist.

   Registers and strings
       Much  mm behavior can be configured by registers and strings.  A regis‐
       ter is assigned with the nr request.

              .nr ident [±]n [i]

       ident is the name of the register, and n is the value to  be  assigned.
       n can be prefixed with a plus or minus sign if incrementation or decre‐
       mentation  (respectively)  of the register’s existing value by n is de‐
       sired.  If assignment of a (possibly) negative n is  required,  further
       prefix it with a zero or enclose it in parentheses.  If i is specified,
       the register is automatically modified by i prior to interpolation if a
       plus or minus sign is included in the escape sequence as follows.

              \n[±][ident]

       i  can  be negative; it combines algebraically with the sign in the in‐
       terpolation escape sequence.

       Strings are defined with the ds request.

              .ds ident contents

       contents consumes everything up to  the  end  of  the  line,  including
       trailing  spaces.  It is a good practice to end contents with a comment
       escape sequence (\") so that extraneous spaces do  not  intrude  during
       document maintenance.  To include leading spaces in contents, prefix it
       with  a  double quote.  Strings are interpolated with the \* escape se‐
       quence.

              \*[ident]

       Register and string name spaces are distinct, but  strings  and  macros
       share  a  name  space.   Defining  a string with the same name as an mm
       macro is not supported and may cause incorrect rendering, the  emission
       of diagnostic messages, and an error exit status from troff.

   Register format
       A register is interpolated using Arabic numerals if no other format has
       been  assigned  to  it.   Assign a format to a register with the af re‐
       quest.

              .af R c

       R is the name of the register, and c is the format.  If c is a sequence
       of Arabic numerals, their quantity defines a zero‐padded minimum  width
       for the interpolated register value.

              Form   Sequence
              1      0, 1, 2, 3, ..., 10, ...
              001    000, 001, 002, 003, ..., 1000, ...
              i      0, i, ii, iii, iv, ...
              I      0, I, II, III, IV, ...
              a      0, a, b, c, ..., z, aa, ab, ...
              A      0, A, B, C, ..., Z, AA, AB, ...

   Fonts
       In  groff mm, the fonts (or rather, font styles) R (roman), I (italic),
       and B (bold) are mounted at font positions 1, 2, and  3,  respectively.
       Internally, font positions are used for backward compatibility.  From a
       practical  point  of view, it doesn’t make a big difference—a different
       font family can still be selected by invoking groff’s  fam  request  or
       using  its  -f  command‐line option.  On the other hand, if you want to
       replace just, for example, font I  with  Zapf  Chancery  Medium  italic
       (available  on  groff’s pdf and ps output devices), you have to use the
       fp request, replacing the font at position 2 with “.fp 2  ZCMI”).   Be‐
       cause the cover sheet, memorandum type, and refer(1) integration macros
       explicitly request fonts named B, I, and R, you will also need to remap
       these font names with the ftr request, for instance with “.ftr I ZCMI”.

Macros
       An  explicitly  empty  argument  may be specified with a pair of double
       quotes; to call a macro XX with an empty second argument but  non‐empty
       first and third ones, you could input the following.

              .XX foo "" baz

       Macro names longer than two characters are GNU extensions; some shorter
       names  were not part of DWB mm’s published interface but are documented
       aspects of groff mm.

       )E level text
              Add heading text text to the table of contents with level, which
              is either 0 or in the range 1 to 7.  See also H.   This  undocu‐
              mented  DWB mm macro is exposed by groff mm to enable customized
              tables of contents.

       1C [1] Format page text in one column.  The page is broken.  A 1  argu‐
              ment  suppresses  this  break; its use may cause body text and a
              pending footnote to overprint.  See 2C, MC, and NCOL.

       2C     Begin two‐column formatting.  This is a special case of MC.  See
              1C and NCOL.

       AE     Abstract end; stop collecting abstract text.  See AS.

       AF [firm‐name]
              Specify firm associated with the document.  At most one  can  be
              declared;  the  firm name is used by memorandum types and avail‐
              able to cover sheets.  AF terminates a  document  title  started
              with TL, and can be called without an argument for that purpose.
              See MT and COVER.

       AL [type [text‐indent [1]]]
              Begin an auto‐incrementing numbered list.  Item numbers start at
              one.   The type argument assigns the register format (see above)
              of the list item enumerators.  The default is 1.  An  explicitly
              empty  type  also indicates the default.  A text‐indent argument
              overrides register Li.  A third argument  suppresses  the  blank
              line  that  normally precedes each list item.  Use LI to declare
              list items, and LE to end the list.

       APP [id [title]]
              Begin an appendix.  If the identifier id is omitted, it  is  in‐
              cremented  (or  initialized, if necessary).  The register format
              used for id is “A”.  The page is broken.  The register  Aph  de‐
              termines  whether  an  appendix heading is then formatted.  This
              heading uses the string App followed by id.   Appendices  appear
              in  any table of contents (see TC).  The string Apptxt is set to
              title if the latter is present, and made empty otherwise.

       APPSK id n [title]
              As APP, but increment the page number by n.  Use this  macro  to
              “skip  pages”  when diagrams or other materials not formatted by
              troff are included in appendices.

       AS [placement [indentation]]
              Abstract start; begin collecting abstract.  Input up to the next
              AE call is included in the abstract.  placement  influences  the
              location of the abstract on the cover sheet of a memorandum (see
              MT).   COVER, by contrast, ignores placement by default, but can
              be customized to interpret it.

              placement   Effect
              0           The abstract appears on page 1 and  cover  sheet  if
                          the  document is a “released paper” memorandum (“.MT
                          4”); otherwise, it appears on page 1 without a cover
                          sheet.
              1           The abstract appears only on the cover  sheet  (“.MT
                          4” only).

              An  abstract  does  not  appear at all in external letters (“.MT
              5”).  A placement of 2 was supported by DWB mm  but  is  not  by
              groff mm.

              A  second  argument increases the indentation by indentation and
              reduces the line length by twice this amount.  A scaling unit of
              ens is assumed.  The default is 0.

       AST [caption]
              Set the caption above the abstract to caption, or  clear  it  if
              there is no argument.  The default is “ABSTRACT”.

       AT title ...
              Specify  author’s title(s).  If present, AT must appear just af‐
              ter the corresponding author’s AU.  Each title occupies an  out‐
              put  line  beneath the author’s name in the signature block used
              by LT letters (see SG) and in MT memoranda.  The ms cover  sheet
              style also uses it.

       AU [name [initials [loc [dept [ext [room [arg1 [arg2 [arg3]]]]]]]]]
              Specify author.  AU terminates a document title started with TL,
              and  can  be  called without arguments for that purpose.  Author
              information is used by cover sheets, MT memoranda, and SG.  Fur‐
              ther arguments comprise initials,  location,  department,  tele‐
              phone extension, room number or name, and up to three additional
              items.  Repeat AU to identify multiple authors.

              Use WA/WE instead to identify the author for documents employing
              LT.

       AV [name [1]]
              Format approval lines for a handwritten signature and date.  Two
              horizontal rules are drawn, with the specified name and the text
              of the string Letdate beneath them.  Above these rules, the text
              in  the  string  Letapp is formatted; a second argument replaces
              this text with a blank line.  See LT.

       AVL [name]
              As AV, but the date, date rule, and approval notation Letapp are
              omitted.

       B [bold‐text [previous‐font‐text]] ...
              Join bold‐text in boldface with previous‐font‐text in the previ‐
              ous font, without space between the arguments.  If no arguments,
              switch font to bold style.

       B1     Begin boxed, kept display.  The text is indented one  character,
              and  the  right  margin is one character shorter.  This is a GNU
              extension.

       B2     End boxed, kept display.  This is a GNU extension.

       BE     End bottom block; see BS.

       BI [bold‐text [italic‐text]] ...
              Join bold‐text in boldface with italic‐text in italics,  without
              space between the arguments.

       BL [text‐indent [1]]
              Begin  bulleted  list.   Items  are prefixed with a bullet and a
              space.  A text‐indent argument overrides register Pi.  A  second
              argument  suppresses  blank  lines between items.  Use LI to de‐
              clare list items, and LE to end the list.

       BR [bold‐text [roman‐text]] ...
              Join bold‐text in boldface with roman‐text in roman style, with‐
              out space between the arguments.

       BS     Begin bottom block.  Input is collected until BE is called,  and
              output between the footnote area and footer of each page.

       BVL [text‐indent [mark‐indent [1]]]
              Begin broken variable‐item (or “tagged”) list.  Each item is ex‐
              pected  to supply its own mark.  The line is always broken after
              the mark; contrast VL.  text‐indent sets the indentation of  the
              text,  and mark‐indent the distance from the current list inden‐
              tation to the mark.  A third argument suppresses the blank  line
              that  normally  precedes each list item.  Use LI to declare list
              items, and LE to end the list.

       COVER [style]
              Begin a cover page description.  COVER must  appear  before  the
              body text (or main matter) of a document.  The argument style is
              used to construct the file name /usr/share/groff/1.23.0/tmac/mm/
              style.cov  and  load it with the mso request.  The default style
              is ms; the ms.cov file prepares a cover page resembling those of
              the ms package.  A .cov file must define a COVEND macro, which a
              document must call at the end of  the  cover  description.   Use
              cover  description macros in the following order; only TL and AU
              are required.

              .COVER
              .TL
              .AF
              .AU
              .AT
              .AS
              .AE
              .COVEND

       COVEND End the cover description.

       DE     End static or floating display begun with DS or DF.

       DF [format [fill [right‐indentation]]]
              Begin floating display.  A floating display is saved in a  queue
              and  output  in  the order entered.  Arguments are handled as in
              DS.  Floating displays cannot be nested.  Placement of  floating
              displays is controlled by the registers De and Df.

       DL [text‐indent [1]]
              Begin  dashed  list.   Items  are prefixed with an em dash and a
              space.  A text‐indent argument overrides register Pi.  A  second
              argument  suppresses  blank  lines between items.  Use LI to de‐
              clare list items, and LE to end the list.

       DS [format [fill [right‐indentation]]]
              Begin static display.  Input until DE  is  called  is  collected
              into  a  display.  The display is output on a single page unless
              it is taller than the height of the  page.   DS  can  be  nested
              (contrast with DF).

              format   Effect
              none     Do not indent the display.
              L        Do not indent the display.
              I        Indent text by \n[Si].
              C        Center each line.
              CB       Center the whole display as a block.
              R        Right‐adjust the lines.
              RB       Right‐adjust the whole display as a block.

              The values “L”, “I”, “C”, and “CB” can also be specified as “0”,
              “1”, “2”, and “3”, respectively, for compatibility with DWB mm.

              fill   Effect
              none   Disable filling.
              N      Disable filling.
              F      Enable filling.

              “N”  and “F” can also be specified as “0” and “1”, respectively,
              for compatibility with DWB mm.

              A third argument reduces the line length by right‐indentation.

              mm normally places blank lines before  and  after  the  display.
              Set register Ds to 0 to suppress these.

       EC [title [override [flag [refname]]]]
              Caption  an  equation.   The caption consists of the string Liec
              followed by an automatically incrementing counter stored in  the
              register Ec, punctuation configured by the register Of, then ti‐
              tle  (if any).  Use the af request to configure Ec’s number for‐
              mat.  override and flag alter the equation  number  as  follows.
              Omitting flag and specifying 0 in its place are equivalent.

              flag   Effect
              0      Prefix number with override.
              1      Suffix number with override.
              2      Replace number with override.

              Equation  captions are centered irrespective of the alignment of
              any enclosing display.

              refname stores the equation number using SETR;  it  can  be  re‐
              treived  with  “.GETST  refname”.  This argument is a GNU exten‐
              sion.

              Captioned equations are listed in a table of contents  (see  TC)
              if the Boolean register Le is true.  Such a list uses the string
              Le as a heading.

       EF ["'left'center'right'"]
              Define  the  even‐page footer, which is formatted just above the
              normal page footer on even‐numbered pages.  See PF.  EF  defines
              the string EOPef.

       EH ["'left'center'right'"]
              Define  the  even‐page header, which is formatted just below the
              normal page header on even‐numbered pages.  See PH.  EH  defines
              the string TPeh.

       EN     End equation input preprocessed by eqn(1); see EQ.

       EOP    If  defined,  this macro is called in lieu of normal page footer
              layout.  Headers and footers are formatted in a  separate  envi‐
              ronment.  See TP.

              Strings available to EOP
              ─────────────────────────
              EOPf     argument to PF
              EOPef    argument to EF
              EOPof    argument to OF

       EPIC [-L] width height [name]
              Draw  a box with the given width and height.  It also prints the
              text name or a default string if name is not specified.  This is
              used to include external pictures; just give  the  size  of  the
              picture.   -L left‐aligns the picture; the default is to center.
              See PIC.

       EQ [label]
              Start equation input preprocessed by eqn(1).  EQ  and  EN  macro
              calls  bracket  an  equation  region.  Such regions must be con‐
              tained in displays (DS/DE), except when the region is used  only
              to  configure  eqn and not to produce output.  If present, label
              appears aligned to the right and centered vertically within  the
              display;  see register Eq.  If multiple eqn regions occur within
              a display, only the last label (if any) is used.

       EX [title [override [flag [refname]]]]
              Caption an exhibit.  Arguments are handled  analogously  to  EC.
              The  register  Ex  is the exhibit counter.  The string Liex pre‐
              cedes the exhibit number and any title.   Exhibit  captions  are
              centered irrespective of the alignment of any enclosing display.

              Captioned exhibits are listed in a table of contents (see TC) if
              the Boolean register Lx is true.  Such a list uses the string Lx
              as a heading.

       FC [closing‐text]
              Output  the  string Letfc, or the specified closing‐text, as the
              formal closing of a letter.

       FD [arg [1]]
              Configure display of footnotes.  The first argument encodes  en‐
              ablement  of automatic hyphenation, adjustment to the right mar‐
              gin, indentation of footnote text, and left‐ vs. right‐alignment
              of the footnote label within the space allocated for it.

              arg   Hyphenate?   Adjust?   Indent?   Label alignment
              0     no           yes       yes       left
              1     yes          yes       yes       left
              2     no           no        yes       left
              3     yes          no        yes       left
              4     no           yes       no        left
              5     yes          yes       no        left
              6     no           no        no        left
              7     yes          no        no        left
              8     no           yes       yes       right
              9     yes          yes       yes       right
              10    no           no        yes       right
              11    yes          no        yes       right

              An arg greater than 11 is treated as 0.  mm’s default is 0.

              If a second argument, conventionally 1, is given, footnote  num‐
              bering  is reset when a first‐level heading is encountered.  See
              FS.

       FE     End footnote; see FS.

       FG [title [override [flag [refname]]]]
              Caption a figure.  Arguments are handled analogously to EC.  The
              register Fg is the figure counter.  The string Lifg precedes the
              figure number and any title.  Figure captions are centered irre‐
              spective of the alignment of any enclosing display.

              Captioned figures are listed in a table of contents (see TC)  if
              the Boolean register Lf is true.  Such a list uses the string Lf
              as a heading.

       FS [label]
              Start  footnote.   Input  until FE is called is collected into a
              footnote.  By  default,  footnotes  are  automatically  numbered
              starting  at 1; the number is available in register :p and, with
              a trailing period, in string F.  This string precedes the  foot‐
              note  text  at  the bottom of the column or page.  Footnotes are
              vertically separated by the product of registers Fs and Lsp.  In
              groff mm, footnotes may be used in displays.

              A label argument replaces the contents of the string F; it  need
              not  be numeric.  In this event, the footnote marker in the body
              text must be explicitly written.

       GETHN refname [varname]
              Include the heading number where the corresponding  “.SETR  ref‐
              name” was placed.  This is displayed as “X.X.X.” in pass 1.  See
              INITR.  If varname is used, GETHN sets the string varname to the
              heading number.

       GETPN refname [varname]
              Include  the page number where the corresponding “.SETR refname”
              was placed.  This is displayed as “9999” in pass 1.  See  INITR.
              If  varname  is  used, GETPN sets the string varname to the page
              number.

       GETR refname
              Combine GETHN and GETPN with the text “chapter”  and  “,  page”.
              The string Qrf contains the text for the cross reference:

                     .ds Qrf See chapter \\*[Qrfh], page \\*[Qrfp].

              Qrf may be changed to support other languages.  Strings Qrfh and
              Qrfp  are  set  by GETR and contain the page and heading number,
              respectively.

       GETST refname [varname]
              Include the string saved with  the  second  argument  to  .SETR.
              This  is  a  dummy  string in pass 1.  If varname is used, GETST
              sets it to the saved string.  See INITR.

       H level [title [suffix]]
              Set a numbered section heading at level.  mm  produces  numbered
              heading  marks  of the form a.b.c..., with up to fourteen levels
              of nesting.  Each level’s number  increases  automatically  with
              each  H  call and is reset to zero when a more significant level
              is specified.  “1” is the most significant or coarsest  division
              of  the  document.  Text after an H call is formatted as a para‐
              graph; calling P is unnecessary.

              title specifies an optional title; it must be  double‐quoted  if
              it  contains  spaces.  mm appends suffix to title in the body of
              the document, but omits it from any table of contents (see  TC).
              This  facility  can be used to annotate the heading title with a
              footnote.  suffix should not interpolate the F string; specify a
              footnote mark explicitly.  See FS.

              Heading behavior is highly configurable.  Several registers  set
              a  threshold,  where  heading  levels  at or below the threshold
              value are handled in one way, and those above it  another.   For
              example,  a heading level within the threshold of register Cl is
              included in the table of contents (see TC).

              Heading layout.  Register Ej sets a threshold for page  breaking
              (ejection) prior to a heading.  If not preceded by a page break,
              a  heading level below the threshold in register Hps is preceded
              by the amount of vertical space in register  Hps1,  and  by  the
              amount  in Hps2 otherwise.  The Hb register sets a threshold be‐
              low which a break occurs after the heading, and register Hs sets
              a threshold below which vertical space follows it.  If the head‐
              ing level is not less than both of these, a  run‐in  heading  is
              produced;  paragraph text follows on the same output line.  Oth‐
              erwise, register Hi configures the  indentation  of  text  after
              headings.   Threshold register Hc enables the centering of head‐
              ings; a heading level below both of the Hb and Hc thresholds  is
              centered.

              Heading  typeface  and size.  The fonts used for heading numbers
              and titles at each level are configured by the HF  string.   The
              string  HP  likewise  assigns a type size to each heading level.
              The vertical spacing used by headings may be controlled  by  the
              user‐definable macros HX and/or HZ.

              Heading  number  format.   Registers  named H1 through H14 store
              counters for each heading level.  Their values are printed using
              Arabic numerals by default; see  HM.   The  heading  levels  are
              catenated with dots for formatting; to typeset only the deepest,
              set  the  Ht  register.  Heading numbers are not suffixed with a
              trailing dot except when only the first level is output; to omit
              a dot in this case as well, clear the H1dot register.

              Customizing heading behavior.  mm calls hook  macros  to  enable
              further  customization  of  headings.  (DWB mm called these “ex‐
              its”.)  They can be used to change the heading’s mark (the  num‐
              bered  portion  before any heading title), its vertical spacing,
              and its vertical space requirements (for instance, to require  a
              minimum  quantity  of  subsequent  output  lines).   Define hook
              macros in expectation of the following parameters.  The argument
              declared‐level is the level argument to H, or 0  for  unnumbered
              headings  (see  HU).  actual‐level is the same as declared‐level
              for numbered headings, and the value of register Hu  for  unnum‐
              bered headings.  title is the corresponding argument to H or HU.

              HX declared‐level actual‐level title
                     mm  calls HX before setting the heading.  Your definition
                     may alter }0, }2, and ;3.

                     }0 (string)
                            contains the heading mark plus two spaces  if  de‐
                            clared‐level is non‐zero, and otherwise is empty.

                     ;0 (register)
                            encodes a position for the text after the heading.
                            0  means that the heading is to be run in, 1 means
                            that a break is to  occur  before  the  text,  and
                            2 means that vertical space is to separate heading
                            and text.

                     }2 (string)
                            is the suffix that separates a run‐in heading from
                            the  text.   It contains two spaces if register ;0
                            is 0, and otherwise is empty.

                     ;3 (register)
                            contains the vertical space required for the head‐
                            ing to be typeset.  If that amount is  not  avail‐
                            able,  the  page  is  broken prior to the heading.
                            The default is 2v.

              HY declared‐level actual‐level title
                     mm calls HY after  determing  the  heading  typeface  and
                     size.  It could be used to change indentation.

              HZ declared‐level actual‐level title
                     mm  calls  HZ after formatting the heading, just before H
                     or HU returns.  It could  be  used  to  change  the  page
                     header to include a section heading.

       HC [hyphenation‐character]
              Set  hyphenation  character.   Default value is “\%”.  Resets to
              the default if called  without  argument.   Hyphenation  can  be
              turned  off  by setting register Hy to 0 at the beginning of the
              file.

       HM [arg1 [arg2 [... [arg14]]]]
              Set the heading mark style.  Each argument assigns the specified
              register format (see above) to the corresponding heading  level.
              The  default  is 1 for all levels.  An explicitly empty argument
              also indicates the default.

       HU heading‐text
              Set an unnumbered section heading.  Except for a heading number,
              it is treated as a numbered heading of the level stored in  reg‐
              ister Hu; see H.

       I [italic‐text [previous‐font‐text]] ...
              Join  italic‐text in italics with previous‐font‐text in the pre‐
              vious font, without space between the arguments.   If  no  argu‐
              ments, switch font to italic style.

       IA [recipient‐name [title]]
              Specify the inside address in a letter.  Input is collected into
              the inside address until IE is called, and then output.  You can
              specify  multiple  recipients  with  empty IA/IE pairs; only the
              last address is used.  The arguments give each recipient a  name
              and title.  See LT.

       IB [italic‐text [bold‐text]] ...
              Join  italic‐text in italics with bold‐text in boldface, without
              space between the arguments.

       IE     End the inside address begun with IA.

       IND argument ...
              If the Boolean register Ref is true, write an index entry  as  a
              specially  prepared  roff  comment to the standard error stream,
              with each argument separated from its predecessor by a tab char‐
              acter.  The entry’s location information is arranged as  config‐
              ured by the most recent INITI call.

       INDP   Output the index set up by INITI and populated by IND calls.  By
              default, INDP calls SK and writes a centered caption interpolat‐
              ing  the  string  Index.  It then disables filling and calls 2C;
              afterward, it restores filling and calls 1C.

              Define macros to customize this behavior.  INDP calls TXIND  be‐
              fore  the  caption,  TYIND  instead  of writing the caption, and
              TZIND after formatting the index.

       INITI location‐type file‐name [macro]
              Initialize groff mm’s indexing system.   Argument  location‐type
              selects how the location of each index entry is reported.  file‐
              name populates an internal string used later by INDP.

              location‐type   Entry format
              N               page number
              H               heading mark
              B               page number, tab character, heading mark

              If  macro  is  specified, it is called for each index entry with
              the arguments given to IND.

       INITR id
              Initialize the cross reference  macros.   Cross  references  are
              written to the standard error stream, which should be redirected
              into  a  file  named id.qrf.  mmroff(1) handles this and the two
              formatting passes it requires.  The first pass identifies  cross
              references, and the second one includes them.

              See SETR, GETPN, and GETHN.

       IR [italic‐text [roman‐text]] ...
              Join  italic‐text  in  italics  with  roman‐text in roman style,
              without space between the arguments.

       ISODATE [0]
              Use ISO 8601 format for the date string DT used  by  some  cover
              sheet and memorandum types; that is, YYYY‐MM‐DD.  Must be called
              before  ND to be effective.  If given an argument of 0, the tra‐
              ditional date format for the groff locale is used; this is  also
              the default.

       LB text‐indent mark‐indent pad type [mark [pre‐item‐space [pre‐list‐
       space]]]
              Begin  list.  The macros AL, BL, BVL, DL, ML, RL, and VL call LB
              in various ways; they are simpler to use and may be preferred if
              they suit the desired purpose.

              The nesting level of lists is tracked by mm; the outermost level
              is 0.  The text of each list item is  indented  by  text‐indent;
              the default is taken from the Li register (in ens).  Each item’s
              mark is indented by mark‐indent; the default is 0n.  The mark is
              normally left‐aligned.  If pad is greater than zero, mark‐indent
              is  overridden such that pad ens of space follow the mark.  type
              selects one of six possible ways to display the mark.

              type   Output for a mark “x”
              1      x.
              2      x)
              3      (x)
              4      [x]
              5      <x>
              6      {x}

              If type is 0 and mark is unspecified, the items are set  with  a
              hanging  indent.   Otherwise,  mark  is  interpreted as a string
              defining the mark.  If type is greater than zero, items are  au‐
              tomatically  numbered; mark is interpreted as a register format.
              The default type is 0.

              The last two arguments manage vertical space.  Unless  a  list’s
              nesting  level  is  greater  than  the value of register Ls, its
              items are preceded by pre‐item‐space multiplied by the  register
              Lsp;  the  default is 1.  LB precedes the list by pre‐list‐space
              multiplied by the register Lsp; the default is 0.

       LC [list‐level]
              Clear list state.  Active lists are terminated as  if  with  LE,
              either  all  (the  default) or only those from the current level
              down to list‐level if specified.  H calls LC automatically.

       LE [1] End list.  The current list is terminated.   An  argument  of  1
              causes  vertical  space  in the amount of register Lsp to follow
              the list.

       LI [mark [item‐mark‐mode]]
              Begin a list item.  Input is collected into a  list  item  until
              the  current  list  is terminated or LI is called again.  By de‐
              fault, the item’s text is preceded by any mark configured by the
              current list.  If only mark is specified, it replaces  the  con‐
              figured mark.  A second argument prefixes mark to the configured
              mark;  an  item‐mark‐mode value of 1 places an unbreakable space
              after mark, while a value of 2 does not (rendering the two adja‐
              cent).  Also see register Limsp.

       LO option [value]
              Specify letter options; see LT.  Standard options  are  as  fol‐
              lows.  See IA regarding the inside address and string DT regard‐
              ing the date.

              option   Effect
              AT       Attention; put contents of string LetAT and value left‐
                       aligned after the inside address.
              CN       Confidential;  put  value, or contents of string LetCN,
                       left‐aligned after the date.
              RN       Reference; put contents of string LetRN and value after
                       the confidental notation (if any) and the date, aligned
                       with the latter.
              SA       Salutation; put value, or  contents  of  string  LetSA,
                       left‐aligned after the inside address and the confiden‐
                       tal notation (if any).
              SJ       Subject;  put  contents of string LetSJ and value left‐
                       aligned after the inside address and the attention  and
                       salutation  notations  (if  any).  In letter type “SP”,
                       LetSJ is ignored and value is set in full capitals.

       LT [style]
              Format a letter in the designated style, defaulting to  BL  (see
              below).  A letter begins with the writer’s address (WA/WE), fol‐
              lowed  by the date (ND), the inside address (IA/IE), the body of
              the letter (P and other general‐purpose mm macros),  the  formal
              closing (FC), the signature (SG), and notations (NS/NE).  Any of
              these may be omitted.  Letter options specified with LO add fur‐
              ther  annotations, which are extensible; see section “Internals”
              below.

              style   Description
              BL      Blocked: the writer’s address, date, formal closing, and
                      signature are  indented  to  the  center  of  the  line.
                      Everything else is left‐aligned.
              SB      Semi‐blocked:  as  BL,  but the first line of each para‐
                      graph is indented by 5m.
              FB      Fully blocked: everything begins at the left margin.
              SP      Simplified: as FB, but a formal closing is omitted,  and
                      the signature is set in full capitals.

       MC column‐width [gutter‐width]
              Begin  multi‐column layout.  groff mm creates as many columns of
              column‐width as the line length will  permit.   gutter‐width  is
              the  interior  spacing  between columns.  It defaults to column‐
              width/15.  1C returns to single‐column layout.  MC is a GNU  ex‐
              tension.  See MULB for an alternative.

       ML mark [text‐indent [1]]
              Start  a  list  with the mark argument preceding each list item.
              text‐indent overrides the default indentation of the list  items
              set  by  register Li.  If a third argument, conventionally 1, is
              given, the blank line that normally precedes each list  item  is
              suppressed.   Use  LI  to  declare list items, and LE to end the
              list.

       MT [type [addressee]]
              Select memorandum type.  These correspond  to  formats  used  by
              AT&T  Bell  Laboratories, where the mm package was initially de‐
              veloped, affecting the document layout.  Some of these  included
              a cover page with a caption categorizing the document.  groff mm
              uses  type  to  construct the file name /usr/share/groff/1.23.0/
              tmac/mm/type.MT and load it with the  mso  request.   Memorandum
              types 0 to 5 are supported; any other value of type is mapped to
              type  6.   If  type  is omitted, 0 is implied.  addressee sets a
              string analogous to one used by AT&T cover sheet macros that are
              not implemented in groff mm.

              type   Description
              0      normal memorandum; no caption
              1      captioned “MEMORANDUM FOR FILE”
              2      captioned “PROGRAMMER’S NOTES”
              3      captioned “ENGINEER’S NOTES”
              4      released paper
              5      external letter

              See COVER for a more flexible cover sheet mechanism.

       MOVE y‐pos [x‐pos [line‐length]]
              Move to a position, setting page  offset  to  x‐pos.   If  line‐
              length is not given, the difference between current and new page
              offset  is used.  Use PGFORM without arguments to return to nor‐
              mal.

       MULB cw1 space1 [cw2 space2] ... cwn
              Begin alternative multi‐column mode.  All column widths must  be
              specified, as must the amount of space between each column pair.
              The arguments’ default scaling unit is n.  MULB uses a diversion
              and operates in a separate environment.

       MULN   Begin next column in alternative column mode.

       MULE   End alternative multi‐column mode and emit the columns.

       NCOL   Move to the start of the next column (only when using 2C or MC).
              Contrast with MULN.

       ND [arg]
              Set the document’s date.  mm does not interpret arg; it can be a
              revision identifier (or empty).

       NE     End notation begun with NS; filling is enabled.

       nP [type]
              Begin a numbered paragraph at heading level two.  See P.

       NS [code [1]]
              Declare  notations,  typically  for letters or memoranda, of the
              type specified by code.  The text corresponding to code is  out‐
              put,  and  filling is disabled until NE is called.  Typically, a
              list of names or attachments lies within NS/NE.  If code is  ab‐
              sent  or does not match one of the values listed under the Letns
              string description below, each line of notations is formatted as
              “Copy (line) to”.  If a second argument,  conventionally  1,  is
              given, code becomes the entire notation and NE is not necessary.
              In  groff  mm, you can set up further notations to be recognized
              by NS; see the strings Letns and Letnsdef below.

       OF ["'left'center'right'"]
              Define the odd‐page footer, which is formatted  just  above  the
              normal  page  footer on odd‐numbered pages.  See PF.  OF defines
              the string EOPof.

       OH ["'left'center'right'"]
              Define the odd‐page header, which is formatted  just  below  the
              normal  page  header on odd‐numbered pages.  See PH.  OH defines
              the string TPoh.

       OP     Make sure that the following text is printed at the  top  of  an
              odd‐numbered  page.   Does not output an empty page if currently
              at the top of an odd page.

       P [type]
              Begin new paragraph.  If type is missing or  0, P sets the para‐
              graph fully left-aligned.  A type of 1 idents the first line  by
              \[Pi]  ens.   Set  the register Pt to select a default paragraph
              indentation style.  The register Ps controls the vertical  spac‐
              ing between paragraphs.

       PE     Picture end; see pic(1).

       PF ["'left'center'right'"]
              Define  the  page footer.  The footer is formatted at the bottom
              of each page; the argument is otherwise as described in PH.   PF
              defines the string EOPf.  See EF, OF, and EOP.

       PGFORM [linelength [pagelength [pageoffset [1]]]]
              Set  line  length,  page length, and/or page offset.  This macro
              can be used for letterheads and similar.   It  is  normally  the
              first  macro call in a file, though it is not necessary.  PGFORM
              can be used without arguments to reset everything after  a  MOVE
              call.  A line break is done unless the fourth argument is given.
              This  can  be  used  to  avoid the page number on the first page
              while setting new width and length.  (It seems as if this  macro
              sometimes doesn’t work too well.  Use the command‐line arguments
              to change line length, page length, and page offset instead.)

       PGNH   Suppress header on the next page.  This macro must be called be‐
              fore  any macros that produce output to affect the layout of the
              first page.

       PH ["'left'center'right'"]
              Define the page header, formatted at the top of  each  page,  as
              the  argument,  where left, center, and right are aligned to the
              respective locations on the line.  A “%” character in arg is re‐
              placed by the page number.  If the argument is absent,  no  page
              header is set.  The default page header is
                     "''- % -''"
              which  centers the page number between hyphens and formats noth‐
              ing at the upper left and right.  Header macros call PX (if  de‐
              fined)  after formatting the header.  PH defines the string TPh.
              See EH, OH, and TP.

       PIC [-B] [-C|-I n|-L|-R] file [width [height]]
              Include PostScript document  file.   The  optional  -B  argument
              draws  a  box  around the picture.  The optional -L, -C, -R, and
              -I n arguments align the picture or indent it by n  (assuming  a
              scaling  unit  of  m).  By default, the picture is left‐aligned.
              Optional width and height arguments resize the picture.  Use  of
              this   macro   requires   two‐pass  processing;  see  INITR  and
              mmroff(1).

       PS     Picture start; see pic(1).

       PY     Picture end with flyback.  Ends a pic(1) picture, returning  the
              vertical position to where it was prior to the picture.  This is
              a GNU extension.

       R [roman‐text [previous‐font‐text]] ...
              Join  roman‐text  in  roman style with previous‐font‐text in the
              previous font, without space between the arguments.  If no argu‐
              ments, switch font to roman style.

       RB [roman‐text [bold‐text]] ...
              Join roman‐text in roman style with bold‐text in boldface, with‐
              out space between the arguments.

       RD [prompt [diversion [string]]]
              Read from standard input to diversion and/or string.   The  text
              is  saved  in  a  diversion named diversion.  Recall the text by
              writing the name of the diversion after a dot on an empty  line.
              A  string  is also defined if string is given.  Diversion and/or
              prompt can be empty ("").

       RF     Reference end.  Ends a reference definition and returns to  nor‐
              mal processing.  See RS.

       RI [roman‐text [italic‐text]] ...
              Join  roman‐text  in  roman  style  with italic‐text in italics,
              without space between the arguments.

       RL [text‐indent [1]]
              Begin reference list.  Each item is preceded by an automatically
              incremented number between square brackets; compare  AL.   text‐
              indent  changes the default indentation.  Use LI to declare list
              items, and LE to end the list.  A second  argument,  convention‐
              ally  1,  suppresses  the blank line that normally precedes each
              list item.

       RP [suppress‐counter‐reset [page‐ejection‐policy]]
              Format a reference page, listing items accumulated within  RS/RF
              pairs.  The reference counter is reset unless the first argument
              is  1.   Normally, page breaks occur before and after the refer‐
              ences are output; the register Rpe configures this behavior, and
              a second argument overrides its value.  TC  calls  RP  automati‐
              cally if references have accumulated.

              References  are  list  items,  and thus are vertically separated
              (see LB).  Setting register Ls to  0  suppresses  this  spacing.
              The string Rp contains the reference page caption.

       RS [reference‐string]
              Begin  an  automatically  numbered reference definition.  By de‐
              fault, references are numbered starting  at  1;  the  number  is
              available  in  register :R.  Interpolate the string Rf where the
              reference mark should be and write the reference  between  RS/RF
              on  an input line after the reference mark.  If reference‐string
              is specified, groff ms also  stores  the  reference  mark  in  a
              string  of that name, which can be interpolated as \*[reference‐
              string] subsequently.

       S [type‐size [vertical‐spacing]]
              Set type size and vertical spacing.  Each argument  is  a  groff
              measurement, using an appropriate scaling unit and an optional +
              or - prefix to increment or decrement the current value.  An ar‐
              gument of P restores the previous value, C indicates the current
              value, and D requests the default.  An empty or omitted argument
              is treated as P.

       SA [mode]
              Set  or restore the default enablement of adjustment.  Specify 0
              or 1 as mode to set a document’s default explicitly;  1  is  as‐
              sumed  by  mm.  Adjustment can be temporarily suspended with the
              na request.  When the H or HU macros are used to format a  head‐
              ing,  or  when SA is called without a mode argument, the default
              adjustment is restored.

       SETR refname [string]
              Remember the current heading and page numbers as refname.  Saves
              string if string is defined.  string is  retrieved  with  GETST.
              See INITR.

       SG [arg [1]]
              Signature  line.   Prints  the  authors name(s) after the formal
              closing.  The  argument  is  appended  to  the  reference  data,
              printed  at either the first or last author.  The reference data
              is the location, department, and initials specified with AU.  It
              is printed at the first author if the second argument is  given,
              otherwise  at the last.  No reference data is printed if the au‐
              thor(s) is specified through WA/WE.  See section “Internals” be‐
              low.

       SK [n] Skip n pages.  If n is 0 or omitted, the page is  broken  unless
              the  drawing  position  is already at the top of a page.  Other‐
              wise, n pages, blank except for any  headers  and  footers,  are
              printed.

       SM text [post]
       SM pre text post
              Format  text  at  a smaller type size, joined with any specified
              pre and post at normal size.

       SP [lines]
              Space vertically.  lines can have any scaling factor, like  “3i”
              or  “8v”.   Several SP calls in a line only produces the maximum
              number of lines, not the sum.  SP  is  ignored  also  until  the
              first  text line in a page.  Add \& before a call to SP to avoid
              this.

       TAB    Reset tab stops to every 5 ens.

       TB [title [override [flag [refname]]]]
              Caption a table.  Arguments are handled analogously to EC.   The
              register  Tb is the table counter.  The string Litb precedes the
              table number and any title.  Table captions are  centered  irre‐
              spective of the alignment of any enclosing display.

              Captioned  tables  are listed in a table of contents (see TC) if
              the Boolean register Lt is true.  Such a list uses the string Lt
              as a heading.

       TC [slevel [spacing [tlevel [tab [h1 [h2 [h3 [h4 [h5]]]]]]]]]
              Output table of contents.   This  macro  is  normally  the  last
              called in the document.  It flushes any pending displays and, if
              any references are pending (see RS), calls RP.  It then begins a
              new  page with the contents caption, stored in the string Licon,
              centered at the top.  The entries follow  after  three  vees  of
              space.  Each entry is a saved section (number and) heading title
              (see  the  Cl  register), along with its associated page number.
              By default, an entry is indented by an amount  corresponding  to
              its  heading level and the maximum heading length encountered at
              that heading level; if defined, the string  Ci  overrides  these
              indentations.   Entries  at  heading  levels up to and including
              slevel are preceded by spacing vees of space.  Entries at  head‐
              ing  levels  up to and including tlevel are followed by a leader
              and a right‐aligned page number.  If the Boolean‐valued tab  ar‐
              gument is true, the leader is replaced with horizontal motion in
              the  same  amount.   For entries above heading level tlevel, the
              page number follows the heading text after a word  space.   Each
              argument  h1...h5  appears  in  order on its own line, centered,
              above the contents caption.  Page numbering restarts  at  1,  in
              register  format  “i”.  If the Oc register is true, numbering of
              these pages is suppressed.

              If TC is called with at most four arguments, it calls the  user‐
              defined  macro  TX (if defined) prior to formatting the contents
              caption, and TY (if defined) instead of formatting the  contents
              caption.

              Analogous  handling  of lists of figures, tables, equations, and
              exhibits is achieved by defining TXxx and TYxx macros, where  xx
              is  “FG”,  “TB”,  “EC”,  or  “EX”, respectively.  Similarly, the
              strings Lifg, Litb, Liex, and Liec determine captions for  their
              respective lists.

       TE     Table end.  See TS.

       TH     End  table  heading.   It is repeated after page breaks within a
              table.  See TS.  The N argument supported by DWB mm is  not  im‐
              plemented by groff mm.

       TL [charging‐case‐number [filing‐case‐number]]
              Begin  document  title.  Input is collected into the title until
              AF or AU is called, and output as directed by  the  cover  page.
              charging‐case‐number and filing‐case‐number are saved for use in
              memorandum types 0 and 5.  See MT.

       TM number ...
              Declare technical memorandum number(s) used by MT.

       TP     If  defined,  this macro is called in lieu of normal page header
              layout.  Headers and footers are formatted in a  separate  envi‐
              ronment.  See EOP.

              Strings available to TP
              ────────────────────────
              TPh     argument to PH
              TPeh    argument to EH
              TPoh    argument to OH

       TS [H] Table  start.   Argument “H” tells mm that the table has a head‐
              ing.  See TE, TH, and tbl(1).

       VERBON [format [type‐size [font]]]
              Begin verbatim display, where characters have equal width.  for‐
              mat controls several parameters.  Add up the values  of  desired
              features; the default is 0.  On typesetting devices, further ar‐
              guments  configure  the type‐size in scaled points, and the face
              (font); the default is CR (Courier roman).

              Value   Effect
              1       Disable the formatter’s escape character (\).
              2       Vertically space before the display.
              4       Vertically space after the display.
              8       Number output lines; call formatter’s  nm  request  with
                      arguments in string Verbnm.
              16      Indent by the amount stored in register Verbin.

       VERBOFF
              End verbatim display.

       VL [text‐indent [mark‐indent [1]]]
              Begin variable‐item (or “tagged”) list.  Each item should supply
              its  own  mark,  or tag.  If the mark is wider than mark‐indent,
              one space separates  it  from  subsequent  text;  contrast  BVL.
              text‐indent  sets  the  indentation of the text, and mark‐indent
              the distance from the current list indentation to the  mark.   A
              third  argument suppresses the blank line that normally precedes
              each list item.  Use LI to declare list items, and LE to end the
              list.

       VM [-T] [top [bottom]]
              Vertical margin.  Increase the top and bottom margin by top  and
              bottom, respectively.  If option -T is specified, set those mar‐
              gins to top and bottom.  If no argument is given, reset the mar‐
              gin  to  zero, or to the default (“7v 5v”) if -T is used.  It is
              highly recommended that macros TP and/or EOP are defined if  us‐
              ing -T and setting top and/or bottom margin to less than the de‐
              fault.  This undocumented DWB mm macro is exposed by groff mm to
              increase user control of page layout.

       WA [writer’s‐name [title]]
              Specify  the writer(s) of an LT letter.  Input is collected into
              the writer’s address until WA is called, and then  output.   You
              can  specify  multiple  writers with empty WA/WE pairs; only the
              last address is used.  The arguments give each writer a name and
              title.

       WC [format ...]
              Control width of footnotes and displays.

              format   Effect
              N        equivalent to “-WF -FF -WD” (default)
              WF       set footnotes at full line length, even  in  two‐column
                       mode
              -WF      set footnotes using column line length
              FF       apply  width of first footnote to encountered to subse‐
                       quent ones
              -FF      footnote width determined by WF and -WF
              WD       set displays at full line length,  even  in  two‐column
                       mode
              -WD      set displays using column line length

       WE     End the writer’s address begun with WA.

Strings
       Many  mm  strings  interpolate predefined, localizable text.  These are
       presented in quotation marks.

       App    “APPENDIX”

       Apptxt stores the title argument to the last APP call.

       BU     interpolates a bullet (see BL).

       Ci     is a list of indentation amounts to use for  table  of  contents
              heading  levels,  overriding  their automatic computation.  Each
              word must be a horizontal measurement (like “1i”) and is  mapped
              one‐to‐one to heading levels 1, 2, and so on.

       DT     The date; set by the ND macro (defaults to the date the document
              is formatted).  The format is the conventional one for the groff
              locale, but see the ISODATE macro and Iso register.

       EM     interpolates an em dash.

       F      interpolates an automatically numbered footnote marker; the num‐
              ber  is  used by the next FS call without an argument.  In troff
              mode, the marker is superscripted; in nroff  mode,  it  is  sur‐
              rounded by square brackets.

       H1txt  Updated by .H and .HU to the current heading text.  Also updated
              in table of contents & friends.

       HF     assigns font identifiers, separated by spaces, to heading levels
              in  one‐to‐one  correspondence.   Each  identifier may be a font
              mounting position, font name, or style name.  Omitted values are
              assumed to be 1.  The default is “2 2 2 2 2 2 2 2 2 2 2 2 2  2”,
              which places all headings in italics.  DWB mm’s default was “3 3
              2 2 2 2 2”.

       HP     assigns  type  sizes,  separated by spaces, to heading levels in
              one‐to‐one correspondence.  Each size is interpreted  in  scaled
              points;  zero  values  are translated to 10.  Omitted values are
              assumed to be 0 (and are translated accordingly).   The  default
              is “0 0 0 0 0 0 0 0 0 0 0 0 0 0”.

       Index  “INDEX”

       Le     “LIST OF EQUATIONS”

       Letfc  “Yours very truly,” (see FC)

       Letapp “APPROVED:” (see AV)

       LetAT  “ATTENTION:” (see LO)

       LetCN  “CONFIDENTIAL” (see LO)

       Letdate
              “Date” (see AV)

       Letns  is  a group of strings structuring the notations produced by NS.
              If the code argument to NS has no corresponding string, the  no‐
              tation   is   included   between   parentheses,   prefixed  with
              Letns!copy, and suffixed with Letns!to.  Observe the spaces  af‐
              ter “Copy” and before “to”.

              NS code   String       Contents
              0         Letns!0      Copy to
              1         Letns!1      Copy (with att.) to
              2         Letns!2      Copy (without att.) to
              3         Letns!3      Att.
              4         Letns!4      Atts.
              5         Letns!5      Enc.
              6         Letns!6      Encs.
              7         Letns!7      Under separate cover
              8         Letns!8      Letter to
              9         Letns!9      Memorandum to
              10        Letns!10     Copy (with atts.) to
              11        Letns!11     Copy (without atts.) to
              12        Letns!12     Abstract Only to
              13        Letns!13     Complete Memorandum to
              14        Letns!14     CC
              —         Letns!copy   Copy (with trailing space)
              —         Letns!to      to (note leading space)

       Letnsdef
              Select  the notation format used by NS when it is given no argu‐
              ment.  The default is “0”.

       LetRN  “In reference to:” (see LO)

       LetSA  “To Whom It May Concern:” (see LO)

       LetSJ  “SUBJECT:” (see LO)

       Lf     “LIST OF FIGURES”

       Licon  “CONTENTS”

       Liec   “Equation”

       Liex   “Exhibit”

       Lifg   “Figure”

       Litb   “TABLE”

       Lt     “LIST OF TABLES”

       Lx     “LIST OF EXHIBITS”

       MO1...MO12
              “January” through “December”

       Qrf    “See chapter \\*[Qrfh], page \\n[Qrfp].”

       Rf     interpolates an automatically numbered reference mark; the  num‐
              ber  is  used by the next RS call.  In troff mode, the marker is
              superscripted; in nroff mode, it is surrounded by square  brack‐
              ets.

       Rp     “REFERENCES”

       Sm     interpolates ℠, the service mark sign.

       Tcst   interpolates  an  indicator of the TC macro’s processing status.
              If TC is not operating, it is empty.   User‐defined  TP  or  EOP
              macros might condition page headers or footers on its contents.

              Value   Meaning
              co      Table of contents
              fg      List of figures
              tb      List of tables
              ec      List of equations
              ex      List of exhibits
              ap      Appendix

       Tm     interpolates ™, the trade mark sign.

       Verbnm supplies  argument(s)  to  the nm request employed by the VERBON
              macro.  The default is “1”.

Registers
       Default register values, where meaningful, are  shown  in  parentheses.
       Many  are  also marked as Boolean‐valued, meaning that they are consid‐
       ered “true” (on, enabled) when they have a positive value, and  “false”
       (off, disabled) otherwise.

       .mgm   indicates that groff mm is in use (Boolean‐valued; 1).

       :p     is an auto‐incrementing footnote counter; see FS.

       :R     is an auto‐incrementing reference counter; see RS.

       Aph    formats  an  appendix  heading (and title, if supplied); see APP
              (Boolean‐valued; 1).

       Au     includes supplemental author information (the third  and  subse‐
              quent  arguments  to  AU)  in memorandum “from” information; see
              COVER and MT (Boolean‐valued; 1).

       Cl     sets the threshold for inclusion of headings in a table of  con‐
              tents.   Headings at levels above this value are excluded; see H
              and TC (2).  The Cl register controls whether a heading is saved
              for output in the table of contents at  the  time  H  or  HU  is
              called;  if  you  change Cl’s value immediately prior to calling
              TC, you are unlikely to get the result you want.

       Cp     suppresses page breaks before lists of captioned equations,  ex‐
              hibits,  figures,  and  tables, and before an index; see EC, EX,
              FG, TB, and INDP (Boolean‐valued; 0).

       D      produces debugging information for the mm package on  the  stan‐
              dard error stream.  A value of 0 outputs nothing; 1 reports for‐
              matting  progress.  Higher values communicate internal state in‐
              formation of increasing verbosity (0).

       De     causes a page break after a floating display is output;  see  DF
              (Boolean‐valued; 0).

       Df     configures  the behavior of DF.  The following values are recog‐
              nized; 4 and 5 do not override the De register (5).

              Value   Effect
              0       Flush pending displays at the end of each  section  when
                      section‐page  numbering  is active, otherwise at the end
                      of the document.
              1       Flush a pending display on the current page or column if
                      there is enough space, otherwise at the end of the docu‐
                      ment.
              2       Flush one pending display at the top  of  each  page  or
                      column.
              3       Flush a pending display on the current page or column if
                      there is enough space, otherwise at the top of the next.
              4       Flush as many pending displays as possible in a new page
                      or column.
              5       Fill  columns  or pages with flushed displays until none
                      remain.

       Ds     puts vertical space in the amount of register Dsp  (if  defined)
              or  Lsp  before  and after each static display; see DS (Boolean‐
              valued; 1).

       Dsp    configures the amount of vertical space placed before and  after
              static displays; see DS and register Ds (undefined).

       Ec     is an auto‐incrementing equation counter; see EC.

       Ej     sets  the threshold for page breaks (ejection) prior to the for‐
              mat of headings.  Headings at levels above this value are set on
              the same page and column if possible; see H (0).

       Eq     aligns an equation label to the left of a display instead of the
              right (Boolean‐valued; 0).

       Ex     is an auto‐incrementing exhibit counter; see EX.

       Fg     is an auto‐incrementing figure counter; see FG.

       Fs     is multiplied by register Lsp to vertically separate  footnotes;
              see FS (1).

       H1...H14
              are  auto‐incrementing  counters  corresponding  to each heading
              level; see H.

       H1dot  appends a period to the number of a level  one  heading;  see  H
              (Boolean‐valued; 1).

       H1h    is  a  copy  of A copy of register register H1, but it is incre‐
              mented just before a page break.  This can be useful in user‐de‐
              fined macros; see H and HX.

       Hb     sets the threshold for breaking  the  line  after  formatting  a
              heading.  Text after headings at levels above this value are set
              on the same output line if possible; see H (2).

       Hc     sets  the threshold for centering a heading.  Headings at levels
              above this value use the prevailing alignment (that is, they are
              not centered); see H (0).

       Hi     configures the indentation of text after headings.  It does  not
              affect  “run‐in” headings.  The following values are recognized;
              see H and P (1).

              Value   Effect
              0       no indentation
              1       indent per the paragraph type
              2       indent to align with heading title

       Hps    sets the heading level threshold for  application  of  preceding
              vertical  space;  see  H.  Headings at levels above the value in
              register Hps use the amount of space in register Hps1; otherwise
              that in Hps2.  The value of Hps should be strictly greater  than
              that of Ej (1).

       Hps1   configures  the  amount  of  vertical  space preceding a heading
              above the Hps threshold; see H (troff devices: 0.5v;  nroff  de‐
              vices: 1v).

       Hps2   configures  the  amount of vertical space preceding a heading at
              or below the Hps threshold; see H (troff devices: 1v; nroff  de‐
              vices: 2v).

       Hs     sets  the  heading level threshold for application of succeeding
              vertical space.  If the heading level is greater  than  Hs,  the
              heading  is  followed  by vertical space in the amount of regis‐
              ter Hss; see H (2).

       Hss    is multiplied by register Lsp to produce  vertical  space  after
              headings above the threshold in register Hs; see H (1).

       Ht     suppresses  output  of  heading  level counters above the lowest
              when the heading is formatted; see H (Boolean‐valued; 0).

       Hu     sets the heading level used by unnumbered headings; see HU (2).

       Hy     enables automatic hyphenation of words (Boolean‐valued; 0).

       Iso    configures the use of ISO 8601 date format  if  specified  (with
              any value) on the command line; see ISODATE.  The default is de‐
              termined by localization files.

       L      defines  the  page length for the document, and must be set from
              the command line.  A scaling unit should be appended.   The  de‐
              fault is that of the selected groff output device.

       Le
       Lf
       Lt
       Lx     configure  the  report  of lists of equation, figure, table, and
              exhibit captions, respectively, after a table of  contents;  see
              TC (Boolean‐valued; Le: 0; Lf, Lt, Lx: 1).

       Letwam sets  the  maximum number of input lines permitted in a writer’s
              address; see WA and WE (14).

       Li     configures the amount of indentation  in  ens  applied  to  list
              items; see LI (6).

       Limsp  inserts a space between the prefix and the mark in automatically
              numbered lists; see AL (Boolean‐valued; 1).

       Ls     sets  a  threshold  for  placement of vertical space before list
              items.  If the list nesting level is greater than this value, no
              such spacing occurs; see LI (99).

       Lsp    configures the base amount of vertical space used for separation
              in the document.  mm applies  this  spacing  to  many  contexts,
              sometimes  with multipliers; see DS, FS, H, LI, and P (troff de‐
              vices: 0.5v; nroff devices: 1v).

       N      configures the header and footer placements used by PH.  The de‐
              fault footer is empty.  If “section‐page” numbering is selected,
              the default header becomes empty and the default footer  becomes
              “x‐y”,  where x is is the section number (the number of the cur‐
              rent first‐level heading) and y the page number within the  sec‐
              tion.   The  following values are recognized; for finer control,
              see PH, PF, EH, EF, OH, and OF, and registers Sectf  and  Sectp.
              Value 5 is a GNU extension (0).

              Value   Effect
              0       Set header on all pages.
              1       Move header to footer on page 1.
              2       Omit header on page 1.
              3       Use “section‐page” numbering style on all pages.
              4       Omit header on all pages.
              5       Use  “section‐page” and “section‐figure” numbering style
                      on all pages.

       Np     causes paragraphs after first‐level headings (only) to  be  num‐
              bered  in  the format s.p, where s is is the section number (the
              number of the current first‐level heading) and p  is  the  para‐
              graph number, starting at 1; see H and P (Boolean‐valued; 0).

       O      defines  the  page  offset of the document, and must be set from
              the command line.  A scaling unit should be appended.   The  de‐
              fault  is .75i on terminal devices.  On typesetters, it is .963i
              or set to 1i by the papersize.tmac package; see groff_tmac(5).

       Oc     suppresses the appearance of page numbers in the table  of  con‐
              tents; see TC (Boolean‐valued; 0).

       Of     selects a separator format within equation, exhibit, figure, and
              table  captions;  see  EC, EX, FG, and TB.  The following values
              are recognized; the spaces shown are unpaddable (0).

              Value   Effect
              0       ".  "
              1       " — "

       P      interpolates the current page number; it is the same  as  regis‐
              ter % except when “section‐page” numbering is enabled.

       Pi     configures the amount of indentation in ens applied to the first
              line of a paragraph; see P (5).

       Pgps   causes  the  type size and vertical spacing set by S to apply to
              headers and footers, overriding the HP string.  If  not  set,  S
              calls  affect  headers and footers only when followed by PH, PF,
              OH, EH, OF, or OE calls (Boolean‐valued; 1).

       Ps     is multiplied by register Lsp to vertically separate paragraphs;
              see P (1).

       Pt     determines when a first‐line indentation is applied to  a  para‐
              graph; see P (0).

              Value   Effect
              0       never
              1       always
              2       always, except immediately after H, DE, or LE

       Ref    is  used  internally to control mmroff(1)’s two‐pass approach to
              index and reference management; see INITI and  RS  (Boolean‐val‐
              ued; 0).

       Rpe    configures the default page ejection policy for reference pages;
              see RP (0).

              Value   Effect
              0       Break the page before and after the list of references.
              1       Suppress page break after the list.
              2       Suppress page break before the list.
              3       Suppress page breaks before and after the list.

       S      defines the type size for the document, and must be set from the
              command  line.   A scaling unit should be appended; p is typical
              (10p).

       Sectf  selects the “section‐figure” numbering style.  Its default is  0
              unless  register N is set to 5 at the command line (Boolean‐val‐
              ued).

       Sectp  selects the “section‐page” numbering style.  Its  default  is  0
              unless register N is set to 3 or 5 at the command line (Boolean‐
              valued).

       Si     configures the amount of display indentation in ens; see DS (5).

       Tb     is an auto‐incrementing table counter; see TB.

       V      defines  the  vertical spacing for the document, and must be set
              from the command line.  A scaling unit should be appended; p  is
              typical.  The default vertical spacing is 120% of the type size.

       Verbin configures  the amount of indentation for verbatim displays when
              indentation is selected; see VERBON (5n).

       W      defines the “width” of the document (that is, the length  of  an
              output  line  with no indentation); it must be set from the com‐
              mand line.  A scaling unit  should  be  appended.   The  default
              is   6i   or   assigned   by  the  papersize.tmac  package;  see
              groff_tmac(5).

Internals
       The LT letter macros call further macros depending on the letter  type,
       with which they are suffixed.  It is therefore possible to define addi‐
       tional letter types, either in the territory‐specific macro file, or as
       local  additions.   LT sets the registers Pt and Pi to 0 and 5, respec‐
       tively.  The following macros must be defined to support a  new  letter
       type.

       let@init_type
              LT  calls  this macro to initialize any registers and other data
              needed by the letter type.

       let@head_type
              formats the letterhead; it is called instead of the  usual  page
              header macro.  Its definition should remove the alias let@header
              unless the letterhead is desired on subsequent pages.

       let@sg_type name title n is‐final [SG‐arg ...]
              SG  calls  this  macro only for letters; MT memoranda have their
              own signature processing.  name and title are specified  through
              WA/WE.   n  is the index of the nth writer, and is‐final is true
              for the last writer to be listed.  Further SG arguments are  ap‐
              pended to the signature line.

       let@fc_type closing
              This  macro  is  called by FC, and has the formal closing as the
              argument.

       LO implements letter options.  It requires that a string named  Lettype
       be  defined, where type is the letter type.  LO then assigns its second
       argument (value) to the string let*lo-type.

Files
       /usr/share/groff/1.23.0/tmac/m.tmac
              is the groff implementation of the memorandum macros.

       /usr/share/groff/1.23.0/tmac/mm.tmac
              is wrapper to load m.tmac.

       /usr/share/groff/1.23.0/tmac/refer-mm.tmac
              implements refer(1) support for mm.

       /usr/share/groff/1.23.0/tmac/mm/ms.cov
              implements an ms‐like cover sheet.

       /usr/share/groff/1.23.0/tmac/mm/0.MT
              implements memorandum types 0–3 and 6.

       /usr/share/groff/1.23.0/tmac/mm/4.MT
              implements memorandum type 4.

       /usr/share/groff/1.23.0/tmac/mm/5.MT
              implements memorandum type 5.

       /usr/share/groff/1.23.0/tmac/mm/locale
              performs any (further) desired necessary localization; empty  by
              default.

Authors
       The GNU version of the mm macro package was written by Jörgen Hägg ⟨jh@
       axis.se⟩ of Lund, Sweden.

See also
       MM - A Macro Package for Generating Documents ⟨https://tkurtbond.github
       .io/troff/mm-all.pdf⟩,  the  DWB  3.3 mm manual, introduces the package
       but does not document GNU extensions.

       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is the primary groff manual.  You can browse it interactively
       with “info groff”.

       groff(1), troff(1), tbl(1), pic(1), eqn(1), refer(1), groff_mmse(7)

groff 1.23.0                      2 July 2023                      groff_mm(7)
───────────────────────────────────────────────────────────────────────────────
groff_mmse(7)           Handbok för diverse information          groff_mmse(7)

Namn
       groff_mmse - svenska ”memorandum” makro för GNU roff

Syntax
       groff -mmse [flaggor ...] [filer ...]
       groff -m mmse [flaggor ...] [filer ...]

Beskrivning
       mmse är en svensk variant av mm. Alla texter är översatta. En  A4  sida
       får  text som är 13 cm bred, 3,5 cm indragning samt är 28,5 cm hög. Det
       finns stöd för brevuppställning enligt svensk standard för vänster  och
       högerjusterad text.

       COVER  kan  använda se_ms som argument. Detta ger ett svenskt försätts‐
       blad. Se groff_mm(7) för övriga detaljer.

Brev
       Tillgängliga brevtyper:

       .LT SVV
              Vänsterställd löptext  med  adressat  i  position  T0  (vänster‐
              ställt).

       .LT SVH
              Högerställd  löptext med adressat i position T4 (passar fönster‐
              kuvert).

       Följande extra LO‐variabler används.

       .LO DNAMN namn
              Anger dokumentets namn.

       .LO MDAT datum
              Mottagarens datum, anges under Ert datum: (LetMDAT).

       .LO BIL sträng
              Anger bilaga, nummer eller sträng med Bilaga (LetBIL)  som  pre‐
              fix.

       .LO KOMP text
              Anger kompletteringsuppgift.

       .LO DBET beteckning
              Anger dokumentbeteckning eller dokumentnummer.

       .LO BET beteckning
              Anger  beteckning (ärendebeteckning i form av diarienummer eller
              liknande).

       .LO SIDOR antal
              Anger totala antalet sidor och skrivs ut  efter  sidnumret  inom
              parenteser.

       Om  makrot .TP är definierat anropas det efter utskrift av brevhuvudet.
       Där lägger man lämpligen in postadress och annat som brevfot.

Skrivet av
       Jörgen Hägg, Lund, Sweden <Jorgen.Hagg@axis.se>

Filer
       /usr/share/groff/1.23.0/tmac/mse.tmac

       /usr/share/groff/1.23.0/tmac/mm/se_*.cov

Se också
       groff_mm(7)

groff 1.23.0                      2 July 2023                    groff_mmse(7)
───────────────────────────────────────────────────────────────────────────────
groff_mom(7)           Miscellaneous Information Manual           groff_mom(7)

Name
       groff_mom - modern macros for document composition with GNU roff

Synopsis
       groff -mom [option ...] [file ...]
       groff -m mom [option ...] [file ...]

Description
       mom is a macro set for groff, designed primarily to  prepare  documents
       for  PDF and PostScript output.  mom provides macros in two categories:
       typesetting and document processing.   The  former  provide  access  to
       groff’s  typesetting  capabilities  in  ways that are simpler to master
       than groff’s requests and escape sequences.  The latter provide  highly
       customizable  markup tags that allow the user to design and output pro‐
       fessional‐looking documents with a minimum of typesetting intervention.

       Files processed with pdfmom(1) produce PDF  documents.   The  documents
       include a PDF outline that appears in the navigation pane panel of doc‐
       ument viewers, and may contain clickable internal and external links.

       Normally.   groff’s  native  PDF driver, gropdf(1), is used to generate
       the output.  When pdfmom is given the “-T ps” option, it still produces
       PDF, but processing is delegated to pdfroff, which uses  groff’s  Post‐
       Script driver, grops(1).  Not all PDF features are available when -T ps
       is given; its primary use is to allow processing of files with embedded
       PostScript images.

       Files processed with groff -mom (or -m mom) format for the device spec‐
       ified  with  the  -T  option.  (In this installation, ps is the default
       output device.)

       mom comes with her own comprehensive documentation in HTML.  A PDF man‐
       ual, “Producing PDFs with groff and mom”, discusses preparation of  PDF
       documents with mom in detail.

Files
       /usr/share/groff/1.23.0/tmac/mom.tmac
              is  a  wrapper  enabling the package to be loaded with “groff -m
              mom”.

       /usr/share/groff/1.23.0/tmac/om.tmac
              implements the package.

       /usr/share/doc/groff-1.23.0/html/mom/toc.html
              is the entry point to the HTML documentation.

       /usr/share/doc/groff-1.23.0/pdf/mom-pdf.pdf
              is “Producing PDFs with groff and mom”, by Deri James and  Peter
              Schaffter.

       /usr/share/doc/groff-1.23.0/examples/mom/*.mom
              are examples of mom usage.

Reference
   Escape sequences
       \*[<colorname>]
              begin using an initialized colour inline

       \*[BCK n]
              move backward in a line

       \*[BOLDER]
              invoke pseudo bold inline (related to macro .SETBOLDER)

       \*[BOLDERX]
              off pseudo bold inline (related to macro .SETBOLDER)

       \*[BU n]
              move  characters  pairs closer together inline (related to macro
              .KERN)

       \*[COND]
              invoke pseudo condensing inline (related to macro .CONDENSE)

       \*[CONDX]
              off pseudo condensing inline (related to macro .CONDENSE)

       \*[CONDSUP]...\*[CONDSUPX]
              pseudo‐condensed superscript

       \*[DOWN n]
              temporarily move downward in a line

       \*[EN-MARK]
              mark initial line of a range of line numbers (for use with  line
              numbered endnotes)

       \*[EXT]
              invoke pseudo extending inline (related to macro .EXTEND)

       \*[EXTX]
              off pseudo condensing inline (related to macro .EXTEND)

       \*[EXTSUP]...\*[EXTSUPX]
              pseudo extended superscript

       \*[FU n]
              move  characters  pairs  further  apart inline (related to macro
              .KERN)

       \*[FWD n]
              move forward in a line

       \*[LEADER]
              insert leaders at the end of a line

       \*[RULE]
              draw a full measure rule

       \*[SIZE n]
              change the point size inline (related to macro .PT_SIZE)

       \*[SLANT]
              invoke pseudo italic inline (related to macro .SETSLANT)

       \*[SLANTX]
              off pseudo italic inline (related to macro .SETSLANT)

       \*[ST<n>]...\*[ST<n>X]
              string tabs (mark tab positions inline)

       \*[SUP]...\*[SUPX]
              superscript

       \*[TB+]
              inline escape for .TN (Tab Next)

       \*[UL]...\*[ULX]
              invoke underlining inline (fixed width fonts only)

       \*[UP n]
              temporarily move upward in a line

   Macros
       .AUTOLEAD
              set the linespacing relative to the point size

       .B_MARGIN
              set a bottom margin

       .BR    break a justified line

       .CENTER
              set line‐by‐line quad centre

       .CONDENSE
              set the amount to pseudo condense

       .EL    break a line without advancing on the page

       .EXTEND
              set the amount to pseudo extend

       .FALLBACK_FONT
              establish a fallback font (for missing fonts)

       .FAM   alias to .FAMILY

       .FAMILY <family>
              set the family type

       .FT    set the font style (roman, italic, etc.)

       .HI [ <measure> ]
              hanging indent

       .HY    automatic hyphenation on/off

       .HY_SET
              set automatic hyphenation parameters

       .IB [ <left measure> <right measure> ]
              indent both

       .IBX [ CLEAR ]
              exit indent both

       .IL [ <measure> ]
              indent left

       .ILX [ CLEAR ]
              exit indent left

       .IQ [ CLEAR ]
              quit any/all indents

       .IR [ <measure> ]
              indent right

       .IRX [ CLEAR ]
              exit indent right

       .JUSTIFY
              justify text to both margins

       .KERN  automatic character pair kerning on/off

       .L_MARGIN
              set a left margin (page offset)

       .LEFT  set line‐by‐line quad left

       .LL    set a line length

       .LS    set a linespacing (leading)

       .PAGE  set explicit page dimensions and margins

       .PAGEWIDTH
              set a custom page width

       .PAGELENGTH
              set a custom page length

       .PAPER <paper_type>
              set common paper sizes (letter, A4, etc)

       .PT_SIZE
              set the point size

       .QUAD  "justify" text left, centre, or right

       .R_MARGIN
              set a right margin

       .RIGHT set line‐by‐line quad right

       .SETBOLDER
              set the amount of emboldening

       .SETSLANT
              set the degree of slant

       .SPREAD
              force justify a line

       .SS    set the sentence space size

       .T_MARGIN
              set a top margin

       .TI [ <measure> ]
              temporary left indent

       .WS    set the minimum word space size

Documentation of details
   Details of inline escape sequences in alphabetical order
       \*[<colorname>]
              begin using an initialized colour inline

       \*[BCK n]
              move backward in a line

       \*[BOLDER]
       \*[BOLDERX]
              Emboldening on/off

              \*[BOLDER] begins emboldening type.  \*[BOLDERX] turns the  fea‐
              ture  off.   Both  are  inline escape sequences; therefore, they
              should not appear as separate lines, but rather be  embedded  in
              text lines, like this:
                     Not \*[BOLDER]everything\*[BOLDERX] is as it seems.

              Alternatively,  if  you  wanted  the  whole line emboldened, you
              should do
                     \*[BOLDER]Not everything is as it seems.\*[BOLDERX]
              Once \*[BOLDER] is invoked, it remains in  effect  until  turned
              off.

              Note:  If  you’re  using  the  document  processing  macros with
              .PRINTSTYLE TYPEWRITE, mom ignores \*[BOLDER] requests.

       \*[BU n]
              move characters pairs closer together inline (related  to  macro
              .KERN)

       \*[COND]
       \*[CONDX]
              Pseudo‐condensing on/off

              \*[COND]  begins  pseudo‐condensing  type.   \*[CONDX] turns the
              feature off.  Both are inline escape sequences; therefore,  they
              should  not  appear as separate lines, but rather be embedded in
              text lines, like this:
                     \*[COND]Not everything is as it seems.\*[CONDX]
              \*[COND] remains in effect until you turn it off with \*[CONDX].

              IMPORTANT: You must turn \*[COND] off before making any  changes
              to the point size of your type, either via the .PT_SIZE macro or
              with  the  \s inline escape sequence.  If you wish the new point
              size to be pseudo‐condensed, simply reinvoke \*[COND] afterward.
              Equally, \*[COND] must be turned off before  changing  the  con‐
              dense percentage with .CONDENSE.

              Note:  If  you’re  using  the  document  processing  macros with
              .PRINTSTYLE TYPEWRITE, mom ignores \*[COND] requests.

       \*[CONDSUP]...\*[CONDSUPX]
              pseudo‐condensed superscript

       \*[DOWN n]
              temporarily move downward in a line

       \*[EN-MARK]
              mark initial line of a range of line numbers (for use with  line
              numbered endnotes)

       \*[EXT]
       \*[EXTX]
              Pseudo‐extending on/off

              \*[EXT]  begins  pseudo‐extending type.  \*[EXTX] turns the fea‐
              ture off.  Both are inline  escape  sequences;  therefore,  they
              should  not  appear as separate lines, but rather be embedded in
              text lines, like this:
                     \*[EXT]Not everything is as it seems.\*[EXTX]
              \*[EXT] remains in effect until you turn it off with \*[EXTX].

              IMPORTANT: You must turn \*[EXT] off before making  any  changes
              to the point size of your type, either via the .PT_SIZE macro or
              with  the  \s inline escape sequence.  If you wish the new point
              size to be pseudo‐extended, simply reinvoke  \*[EXT]  afterward.
              Equally,  \*[EXT]  must be turned off before changing the extend
              percentage with .EXTEND.

              Note: If you are  using  the  document  processing  macros  with
              .PRINTSTYLE TYPEWRITE, mom ignores \*[EXT] requests.

       \*[EXTSUP]...\*[EXTSUPX]
              pseudo extended superscript

       \*[FU n]
              move  characters  pairs  further  apart inline (related to macro
              .KERN)

       \*[FWD n]
              move forward in a line

       \*[LEADER]
              insert leaders at the end of a line

       \*[RULE]
              draw a full measure rule

       \*[SIZE n]
              change the point size inline (related to macro .PT_SIZE)

       \*[SLANT]
       \*[SLANTX]
              Pseudo italic on/off

              \*[SLANT] begins pseudo‐italicizing type.  \*[SLANTX] turns  the
              feature  off.  Both are inline escape sequences; therefore, they
              should not appear as separate lines, but rather be  embedded  in
              text lines, like this:
                     Not \*[SLANT]everything\*[SLANTX] is as it seems.

              Alternatively,  if  you wanted the whole line pseudo‐italicized,
              you’d do
                     \*[SLANT]Not everything is as it seems.\*[SLANTX]

              Once \*[SLANT] is invoked, it remains  in  effect  until  turned
              off.

              Note:  If  you’re  using  the  document  processing  macros with
              .PRINTSTYLE TYPEWRITE, mom underlines pseudo‐italics by default.
              To   change   this   behaviour,   use    the    special    macro
              .SLANT_MEANS_SLANT.

       \*[ST<number>]...\*[ST<number>X]
              Mark positions of string tabs

              The  quad  direction  must  be  LEFT  or  JUSTIFY (see .QUAD and
              .JUSTIFY) or the no‐fill mode set to LEFT in order for these in‐
              lines to function properly.  Please see IMPORTANT, below.

              String tabs need to be marked off with inline  escape  sequences
              before being set up with the .ST macro.  Any input line may con‐
              tain  string  tab  markers.   <number>, above, means the numeric
              identifier of the tab.

              The following shows a sample input line with string tab markers.
                     \*[ST1]De minimus\*[ST1X]non curat\*[ST2]lex\*[ST2X].

              String tab 1 begins at the start of the line and ends after  the
              word time.  String tab 2 starts at good and ends after men.  In‐
              line escape sequences (e.g., font or point size changes, or hor‐
              izontal  movements,  including  padding)  are taken into account
              when mom determines the position and length of string tabs.

              Up to nineteen string tabs may be marked (not necessarily all on
              the same line, of course), and they must be numbered  between  1
              and 19.

              Once  string  tabs have been marked in input lines, they have to
              be set with .ST, after which they may be called, by number, with
              .TAB.

              Note: Lines with string tabs marked off in them are normal input
              lines, i.e. they get printed, just like any input line.  If  you
              want  to  set  up string tabs without the line printing, use the
              .SILENT macro.

              IMPORTANT: Owing to the way  groff  processes  input  lines  and
              turns  them  into  output  lines,  it is not possible for mom to
              guess the correct starting position of string tabs marked off in
              lines that are centered or set flush right.

              Equally, she cannot guess the starting position  if  a  line  is
              fully justified and broken with .SPREAD.

              In  other  words,  in order to use string tabs, LEFT must be ac‐
              tive, or, if .QUAD LEFT or JUSTIFY are active, the line on which
              the string tabs are marked must be broken manually with .BR (but
              not .SPREAD).

              To circumvent this behaviour, I recommend using the PAD  to  set
              up string tabs in centered or flush right lines.  Say, for exam‐
              ple,  you  want  to use a string tab to underscore the text of a
              centered line with a rule.  Rather than this,
                     .CENTER
                     \*[ST1]A line of text\*[ST1X]\c
                     .EL
                     .ST 1
                     .TAB 1
                     .PT_SIZE 24
                     .ALD 3p
                     \*[RULE]
                     .RLD 3p
                     .TQ
              you should do:
                     .QUAD CENTER
                     .PAD "#\*[ST1]A line of text\*[ST1X]#"
                     .EL
                     .ST 1
                     .TAB 1
                     .PT_SIZE 24
                     .ALD 3p
                     \" You can't use \*[UP] or \*[DOWN] with \*[RULE].
                     .RLD 3p
                     .TQ

       \*[SUP]...\*[SUPX]
              superscript

       \*[TB+]
              Inline escape for .TN (Tab Next)

       \*[UL]...\*[ULX]
              invoke underlining inline (fixed width fonts only)

       \*[UP n]
              temporarily move upward in a line

   Details of macros in alphabetical order
       .AUTOLEAD
              set the linespacing relative to the point size

       .B_MARGIN <bottom margin>
              Bottom Margin

              Requires a unit of measure

              .B_MARGIN sets a nominal position at the bottom of the page  be‐
              yond which you don’t want your type to go.  When the bottom mar‐
              gin  is  reached,  mom  starts a new page.  .B_MARGIN requires a
              unit of measure.  Decimal fractions are allowed.  To set a nomi‐
              nal bottom margin of 3/4 inch, enter
                     .B_MARGIN .75i

              Obviously, if you haven’t spaced the type on your pages so  that
              the  last  lines fall perfectly at the bottom margin, the margin
              will vary from page to page.  Usually, but not always, the  last
              line of type that fits on a page before the bottom margin causes
              mom to start a new page.

              Occasionally,  owing  to  a  peculiarity in groff, an extra line
              will fall below the nominal bottom margin.  If you’re using  the
              document processing macros, this is unlikely to happen; the doc‐
              ument  processing macros are very hard‐nosed about aligning bot‐
              tom margins.

              Note: The meaning of .B_MARGIN is slightly different when you’re
              using the document processing macros.

       .FALLBACK_FONT <fallback font> [ ABORT | WARN ]
              Fallback Font

              In the event that you pass an invalid argument to .FAMILY  (i.e.
              a non‐existent family), mom, by default, uses the fallback font,
              Courier  Medium Roman (CR), in order to continue processing your
              file.

              If you’d prefer another fallback font, pass  .FALLBACK_FONT  the
              full  family+font  name of the font you’d like.  For example, if
              you’d rather the fallback font were Times Roman Medium Roman,
                     .FALLBACK_FONT TR
              would do the trick.

              Mom issues a warning whenever a font style set with .FT does not
              exist, either because you haven’t registered the  style  or  be‐
              cause  the  font  style does not exist in the current family set
              with .FAMILY.  By default, mom then aborts, which allows you  to
              correct the problem.

              If  you’d  prefer  that mom not abort on non‐existent fonts, but
              rather continue processing using a fallback font, you  can  pass
              .FALLBACK_FONT  the  argument WARN, either by itself, or in con‐
              junction with your chosen fallback font.

              Some examples of invoking .FALLBACK_FONT:

              .FALLBACK_FONT WARN
                     mom will issue a warning whenever you  try  to  access  a
                     non‐existent  font but will continue processing your file
                     with the default fallback font, Courier Medium Roman.

              .FALLBACK_FONT TR WARN
                     mom will issue a warning whenever you  try  to  access  a
                     non‐existent  font but will continue processing your file
                     with a fallback font of Times Roman Medium  Roman;  addi‐
                     tionally,  TR  will be the fallback font whenever you try
                     to access a family that does not exist.

              .FALLBACK_FONT TR ABORT
                     mom will abort whenever you try to access a  non‐existent
                     font,  and will use the fallback font TR whenever you try
                     to access a family that does not  exist.   If,  for  some
                     reason,   you   want  to  revert  to  ABORT,  just  enter
                     ".FALLBACK_FONT ABORT" and mom will once again  abort  on
                     font errors.

       .FAM <family>
              Type Family, alias of .FAMILY

       .FAMILY <family>
              Type Family, alias of .FAM

              .FAMILY  takes  one  argument:  the name of the family you want.
              Groff comes with a small set of basic families, each  identified
              by a 1‐, 2‐ or 3‐letter mnemonic.  The standard families are:
                     A   = Avant Garde
                     BM  = Bookman
                     H   = Helvetica
                     HN  = Helvetica Narrow
                     N   = New Century Schoolbook
                     P   = Palatino
                     T   = Times Roman
                     ZCM = Zapf Chancery

              The  argument  you  pass  to  .FAMILY is the identifier at left,
              above.  For example, if you want Helvetica, enter
                     .FAMILY H

              Note: The font macro (.FT) lets you specify both the type family
              and the desired font with a single macro.  While  this  saves  a
              few  keystrokes,  I  recommend using .FAMILY for family, and .FT
              for font, except where doing so is genuinely inconvenient.  ZCM,
              for example, only exists in one style: Italic (I).

              Therefore,
                     .FT ZCMI
              makes more sense than setting the family to  ZCM,  then  setting
              the font to I.

              Additional  note:  If  you  are running a groff version prior to
              1.19.2, you must follow all .FAMILY requests with a .FT request,
              otherwise mom will set all type up to the next  .FT  request  in
              the fallback font.

              If  you  are  running groff 1.19.2 or later, when you invoke the
              .FAMILY macro, mom remembers the font style (Roman, Italic, etc)
              currently in use (if the font style exists in  the  new  family)
              and  will continue to use the same font style in the new family.
              For example:
                     .FAMILY BM \" Bookman family
                     .FT I \" Medium Italic
                     <some text> \" Bookman Medium Italic
                     .FAMILY H \" Helvetica family
                     <more text> \" Helvetica Medium Italic

              However, if the font style does not exist in the new family, mom
              will set all subsequent type in the fallback font  (by  default,
              Courier  Medium Roman) until she encounters a .FT request that’s
              valid for the family.

              For example, assuming you don’t have the font  Medium  Condensed
              Roman (mom extension CD) in the Helvetica family:
                     .FAMILY UN \" Univers family
                     .FT CD \" Medium Condensed
                     <some text> \" Univers Medium Condensed
                     .FAMILY H \" Helvetica family
                     <more text> \" Courier Medium Roman!

              In  the  above example, you must follow .FAMILY H with a .FT re‐
              quest that’s valid for Helvetica.

              Please see the Appendices, Adding fonts to groff,  for  informa‐
              tion on adding fonts and families to groff,aswellasto see a list
              of  the  extensions  mom  provides  to groff’s basic R, I, B, BI
              styles.

              Suggestion: When adding families to groff, I recommend following
              the established standard for the naming families and fonts.  For
              example, if you add the Garamond family, name the font files
                     GARAMONDR
                     GARAMONDI
                     GARAMONDB
                     GARAMONDBI
              GARAMOND then becomes a valid family name you can pass to .FAMI‐
              LY.  (You could, of course, shorten GARAMOND to just G, or  GD.)
              R,  I,  B, and BI after GARAMOND are the roman, italic, bold and
              bold‐italic fonts respectively.

       .FONT R | B | BI | <any other valid font style>
              Alias to .FT

       .FT R | B | BI | <any other valid font style>
              Set font

              By default, groff permits .FT to take one of four possible argu‐
              ments specifying the desired font:
                     R = (Medium) Roman
                     I = (Medium) Italic
                     B = Bold (Roman)
                     BI = Bold Italic

              For example, if your family is Helvetica, entering
                     .FT B
              will give you the Helvetica bold  font.   If  your  family  were
              Palatino, you’d get the Palatino bold font.

              Mom  considerably extends the range of arguments you can pass to
              .FT, making it more convenient to add and access fonts  of  dif‐
              fering weights and shapes within the same family.

              Have  a  look  here for a list of the weight/style arguments mom
              allows.  Be aware, though, that you must have  the  fonts,  cor‐
              rectly installed and named, in order to use the arguments.  (See
              Adding fonts to groff for instructions and information.)  Please
              also  read  the  ADDITIONAL NOTE found in the description of the
              .FAMILY macro.

              How mom reacts to an invalid argument to .FT  depends  on  which
              version  of groff you’re using.  If your groff version is 1.19.2
              or later, mom will issue a warning and, depending on how  you’ve
              set  up  the fallback font, either continue processing using the
              fallback font, or abort (allowing you to correct  the  problem).
              In  earlier versions, mom will silently continue processing, us‐
              ing either the fallback font or the font that was in effect pri‐
              or to the invalid .FT call.

              .FT will also accept, as an argument, a  full  family  and  font
              name.

              For example,
                     .FT HB
              will set subsequent type in Helvetica Bold.

              However,  I  strongly recommend keeping family and font separate
              except where doing so is genuinely inconvenient.

              For inline control of fonts, see Inline Escapes, font control.

       .HI [ <measure> ]
              Hanging indent — the optional argument requires a unit  of  mea‐
              sure.

              A hanging indent looks like this:
                     The thousand injuries of Fortunato I had borne as best I
                       could, but when he ventured upon insult, I vowed
                       revenge.  You who so well know the nature of my soul
                       will not suppose, however, that I gave utterance to a
                       threat, at length I would be avenged...
              The first line of text hangs outside the left margin.

              In  order to use hanging indents, you must first have a left in‐
              dent active (set with either .IL or .IB).   Mom  will  not  hang
              text  outside  the left margin set with .L_MARGIN or outside the
              left margin of a tab.

              The first time you invoke .HI, you must give it a  measure.   If
              you  want the first line of a paragraph to hang by, say, 1 pica,
              do
                     .IL 1P
                     .HI 1P
              Subsequent invocations of .HI do not require  you  to  supply  a
              measure; mom keeps track of the last measure you gave it.

              Generally  speaking,  you should invoke .HI immediately prior to
              the line you want hung (i.e.  without  any  intervening  control
              lines).   And  because  hanging  indents  affect  only one line,
              there’s no need to turn them off.

              IMPORTANT: Unlike IL, IR and IB, measures given to .HI  are  NOT
              additive.   Each  time you pass a measure to .HI, the measure is
              treated literally.  Recipe: A numbered list  using  hanging  in‐
              dents

              Note:  mom  has macros for setting lists.  This recipe exists to
              demonstrate the use of hanging indents only.
                     .PAGE 8.5i 11i 1i 1i 1i 1i
                     .FAMILY  T
                     .FT      R
                     .PT_SIZE 12
                     .LS      14
                     .JUSTIFY
                     .KERN
                     .SS 0
                     .IL \w'\0\0.'
                     .HI \w'\0\0.'
                     1.\0The most important point to be considered is whether
                     the answer to the meaning of Life, the Universe, and
                     Everything really is 42.  We have no one's word on the
                     subject except Mr. Adams's.
                     .HI
                     2.\0If the answer to the meaning of Life, the Universe,
                     and Everything is indeed 42, what impact does this have on
                     the politics of representation?  42 is, after all not a
                     prime number.  Are we to infer that prime numbers don't
                     deserve equal rights and equal access in the universe?
                     .HI
                     3.\0If 42 is deemed non‐exclusionary, how do we present
                     it as the answer and, at the same time, forestall debate
                     on its exclusionary implications?

              First, we invoke a left indent with a measure equal to the width
              of 2 figures spaces plus a period (using the \w inline  escape).
              At  this  point, the left indent is active; text afterward would
              normally be indented.  However, we invoke a  hanging  indent  of
              exactly  the  same  width, which hangs the first line (and first
              line only!) to the left of the indent by the same  distance  (in
              this case, that means “out to the left margin”).  Because we be‐
              gin  the first line with a number, a period, and a figure space,
              the actual text (The most important point...) starts at  exactly
              the same spot as the indented lines that follow.

              Notice  that  subsequent invocations of .HI don’t require a mea‐
              sure to be given.

              Paste the example above into a file and preview it with
                     pdfmom filename.mom | ps2pdf - filename.pdf
              to see hanging indents in action.

       .IB [ <left measure> <right measure> ]
              Indent both — the optional argument requires a unit of measure

              .IB allows you to set or invoke a left and a right indent at the
              same time.

              At its first invocation, you must supply a measure for both  in‐
              dents;  at subsequent invocations when you wish to supply a mea‐
              sure, both must be given again.  As with .IL and .IR,  the  mea‐
              sures  are  added  to the values previously passed to the macro.
              Hence, if you wish to change just one of the  values,  you  must
              give an argument of zero to the other.

              A  word  of advice: If you need to manipulate left and right in‐
              dents separately, use a combination of .IL and  .IR  instead  of
              .IB.  You’ll save yourself a lot of grief.

              A  minus sign may be prepended to the arguments to subtract from
              their current values.  The \w inline escape may be used to spec‐
              ify text‐dependent measures, in which case no unit of measure is
              required.  For example,
                     .IB \w'margarine' \w'jello'
              left indents text by the width of the word margarine  and  right
              indents by the width of jello.

              Like  .IL  and .IR, .IB with no argument indents by its last ac‐
              tive values.  See the brief explanation of how mom  handles  in‐
              dents for more details.

              Note:  Calling  a  tab (with .TAB <n>) automatically cancels any
              active indents.

              Additional note: Invoking .IB automatically turns  off  .IL  and
              .IR.

       .IL [ <measure> ]
              Indent left — the optional argument requires a unit of measure

              .IL  indents text from the left margin of the page, or if you’re
              in a tab, from the left edge of the tab.  Once  IL  is  on,  the
              left  indent  is  applied  uniformly to every subsequent line of
              text, even if you change the line length.

              The first time you invoke .IL, you must give it a measure.  Sub‐
              sequent invocations with a measure add to the previous  measure.
              A  minus  sign may be prepended to the argument to subtract from
              the current measure.  The \w inline escape may be used to speci‐
              fy a text‐dependent measure, in which case no unit of measure is
              required.  For example,
                     .IL \w'margarine'
              indents text by the width of the word margarine.

              With no argument, .IL indents by its last active value.  See the
              brief explanation of how mom handles indents for more details.

              Note: Calling a tab (with .TAB <n>)  automatically  cancels  any
              active indents.

              Additional note: Invoking .IL automatically turns off IB.

       .IQ [ <measure> ]
              IQ — quit any/all indents

              IMPORTANT  NOTE: The original macro for quitting all indents was
              .IX.  This usage has been deprecated in favour of IQ.  .IX  will
              continue  to  behave  as before, but mom will issue a warning to
              stderr indicating that you should update your documents.

              As a consequence of this change, .ILX, .IRX and .IBX may now al‐
              so be invoked as .ILQ, .IRQ and .IBQ.  Both  forms  are  accept‐
              able.

              Without  an  argument, the macros to quit indents merely restore
              your original margins and line length.  The measures  stored  in
              the  indent  macros  themselves  are  saved so you can call them
              again without having to supply a measure.

              If you pass these macros the optional argument CLEAR,  they  not
              only restore your original left margin and line length, but also
              clear any values associated with a particular indent style.  The
              next time you need an indent of the same style, you have to sup‐
              ply a measure again.

              .IQ CLEAR, as you’d suspect, quits and clears the values for all
              indent styles at once.

       .IR [ <measure> ]
              Indent right — the optional argument requires a unit of measure

              .IR indents text from the right margin of the page, or if you’re
              in a tab, from the end of the tab.

              The first time you invoke .IR, you must give it a measure.  Sub‐
              sequent  invocations  with  a measure add to the previous indent
              measure.  A minus sign may be prepended to the argument to  sub‐
              tract from the current indent measure.  The \w inline escape may
              be  used  to  specify a text‐dependent measure, in which case no
              unit of measure is required.  For example,
                     .IR \w'jello'
              indents text by the width of the word jello.

              With no argument, .IR indents by its last active value.  See the
              brief explanation of how mom handles indents for more details.

              Note: Calling a tab (with .TAB <n>)  automatically  cancels  any
              active indents.

              Additional note: Invoking .IR automatically turns off IB.

       .L_MARGIN <left margin>
              Left Margin

              L_MARGIN  establishes  the  distance  from  the left edge of the
              printer sheet at which you want your type to start.  It  may  be
              used  any time, and remains in effect until you enter a new val‐
              ue.

              Left indents and tabs are calculated from the value you pass  to
              .L_MARGIN,  hence  it’s  always  a good idea to invoke it before
              starting any serious typesetting.  A  unit  of  measure  is  re‐
              quired.   Decimal  fractions are allowed.  Therefore, to set the
              left margin at 3 picas (1/2 inch), you’d enter either
                     .L_MARGIN 3P
              or
                     .L_MARGIN .5i

              If you use the macros .PAGE, .PAGEWIDTH or .PAPER without invok‐
              ing .L_MARGIN (either before or  afterward),  mom  automatically
              sets .L_MARGIN to 1 inch.

              Note:  .L_MARGIN  behaves in a special way when you’re using the
              document processing macros.

       .MCO   Begin multi‐column setting.

              .MCO (Multi‐Column On) is the macro you use to begin  multi‐col‐
              umn  setting.   It marks the current baseline as the top of your
              columns, for use later  with  .MCR.   See  the  introduction  to
              columns  for an explanation of multi‐columns and some sample in‐
              put.

              Note: Do not confuse .MCO with the .COLUMNS macro in  the  docu‐
              ment processing macros.

       .MCR   Once  you’ve  turned  multi‐columns on (with .MCO), .MCR, at any
              time, returns you to the top of your columns.

       .MCX [ <distance to advance below longest column> ]
              Optional argument requires a unit of measure.

              Exit multi‐columns.

              .MCX takes you out of any tab you were in (by silently  invoking
              .TQ) and advances to the bottom of the longest column.

              Without an argument, .MCX advances 1 linespace below the longest
              column.

              Linespace, in this instance, is the leading in effect at the mo‐
              ment .MCX is invoked.

              If you pass the <distance> argument to .MCX, it advances 1 line‐
              space  below  the  longest  column (see above) PLUS the distance
              specified by the argument.  The argument requires a unit of mea‐
              sure; therefore, to advance an extra 6 points below  where  .MCX
              would normally place you, you’d enter
                     .MCX 6p

              Note:  If you wish to advance a precise distance below the base‐
              line of the longest column, use .MCX with an argument of 0  (ze‐
              ro;  no  unit  of measure required) in conjunction with the .ALD
              macro, like this:
                     .MCX 0
                     .ALD 24p
              The above advances to precisely 24 points below the baseline  of
              the longest column.

       .NEWPAGE

              Whenever  you  want to start a new page, use .NEWPAGE, by itself
              with no argument.  Mom will finish  up  processing  the  current
              page  and  move  you to the top of a new one (subject to the top
              margin set with .T_MARGIN).

       .PAGE <width> [ <length> [ <lm> [ <rm> [ <tm> [ <bm> ] ] ] ] ]

              All arguments require a unit of measure

              IMPORTANT: If you’re using the document processing macros, .PAGE
              must come after .START.  Otherwise, it should go at the top of a
              document, prior to any text.  And remember,  when  you’re  using
              the  document  processing  macros,  top margin and bottom margin
              mean something slightly different than when  you’re  using  just
              the  typesetting  macros (see Top and bottom margins in document
              processing).

              .PAGE lets you establish paper dimensions and page margins  with
              a  single macro.  The only required argument is page width.  The
              rest are optional, but they must appear in order and  you  can’t
              skip  over  any.   <lm>,  <rm>, <tm> and <bm> refer to the left,
              right, top and bottom margins respectively.

              Assuming your page dimensions are 11 inches by  17  inches,  and
              that’s all you want to set, enter
                     .PAGE 11i 17i
              If you want to set the left margin as well, say, at 1 inch, PAGE
              would look like this:
                     .PAGE 11i 17i 1i

              Now  suppose  you also want to set the top margin, say, at 1–1/2
              inches.  <tm> comes after <rm> in the  optional  arguments,  but
              you can’t skip over any arguments, therefore to set the top mar‐
              gin,  you  must also give a right margin.  The .PAGE macro would
              look like this:
                     .PAGE 11i 17i 1i 1i 1.5i
                                      |   |
                     required right---+   +---top margin
                             margin

              Clearly, .PAGE is best used when you want a  convenient  way  to
              tell  mom  just  the dimensions of your printer sheet (width and
              length), or when you want to tell her everything about the  page
              (dimensions and all the margins), for example
                     .PAGE 8.5i 11i 45p 45p 45p 45p
              This  sets  up  an  8½ by 11 inch page with margins of 45 points
              (5/8‐inch) all around.

              Additionally, if you invoke .PAGE with a  top  margin  argument,
              any macros you invoke after .PAGE will almost certainly move the
              baseline  of  the  first line of text down by one linespace.  To
              compensate, do
                     .RLD 1v
              immediately before entering any text, or, if it’s feasible, make
              .PAGE the last macro you invoke prior to entering text.

              Please read the Important note on page dimensions and  papersize
              for information on ensuring groff respects your .PAGE dimensions
              and margins.

       .PAGELENGTH <length of printer sheet>
              tells  mom  how  long your printer sheet is.  It works just like
              .PAGEWIDTH.

              Therefore, to tell mom your printer sheet is 11 inches long, you
              enter
                     .PAGELENGTH 11i
              Please read the important note on page dimensions and  papersize
              for information on ensuring groff respects your PAGELENGTH.

       .PAGEWIDTH <width of printer sheet>

              The argument to .PAGEWIDTH is the width of your printer sheet.

              .PAGEWIDTH  requires  a  unit of measure.  Decimal fractions are
              allowed.  Hence, to tell mom that  the  width  of  your  printer
              sheet is 8½ inches, you enter
                     .PAGEWIDTH 8.5i

              Please  read the Important note on page dimensions and papersize
              for information on ensuring groff respects your PAGEWIDTH.

       .PAPER <paper type>
              provides a convenient way to set the page  dimensions  for  some
              common  printer  sheet  sizes.  The argument <paper type> can be
              one of: LETTER, LEGAL, STATEMENT, TABLOID, LEDGER, FOLIO,  QUAR‐
              TO, EXECUTIVE, 10x14, A3, A4, A5, B4, B5.

       .PRINTSTYLE

       .PT_SIZE <size of type in points>
              Point size of type, does not require a unit of measure.

              .PT_SIZE  (Point  Size)  takes one argument: the size of type in
              points.  Unlike most other macros that  establish  the  size  or
              measure  of something, .PT_SIZE does not require that you supply
              a unit of measure since it’s a near  universal  convention  that
              type  size is measured in points.  Therefore, to change the type
              size to, say, 11 points, enter
                     .PT_SIZE 11
              Point sizes may be fractional (e.g., 10.25 or 12.5).

              You can prepend a plus or  a  minus  sign  to  the  argument  to
              .PT_SIZE, in which case the point size will be changed by + or -
              the  original  value.  For example, if the point size is 12, and
              you want 14, you can do
                     .PT_SIZE +2
              then later reset it to 12 with
                     .PT_SIZE -2
              The size of type can also be changed inline.

              Note: It is unfortunate that the pic  preprocessor  has  already
              taken the name, PS, and thus mom’s macro for setting point sizes
              can’t  use it.  However, if you aren’t using pic, you might want
              to alias .PT_SIZE as .PS, since there’d be no conflict.  For ex‐
              ample
                     .ALIAS PS PT_SIZE
              would allow you to set point sizes with .PS.

       .R_MARGIN <right margin>
              Right Margin

              Requires a unit of measure.

              IMPORTANT:  .R_MARGIN,  if  used,  must   come   after   .PAPER,
              .PAGEWIDTH,  .L_MARGIN,  and/or  .PAGE  (if a right margin isn’t
              given to PAGE).  The reason is that  .R_MARGIN  calculates  line
              length from the overall page dimensions and the left margin.

              Obviously,  it can’t make the calculation if it doesn’t know the
              page width and the left margin.

              .R_MARGIN establishes the amount of space you want  between  the
              end  of  typeset  lines  and  the right hand edge of the printer
              sheet.  In other words, it sets the line length.  .R_MARGIN  re‐
              quires a unit of measure.  Decimal fractions are allowed.

              The  line  length  macro (LL) can be used in place of .R_MARGIN.
              In either case, the last one invoked sets the line length.   The
              choice of which to use is up to you.  In some instances, you may
              find  it  easier to think of a section of type as having a right
              margin.  In others, giving a line length may make more sense.

              For example, if you’re setting a page of type  you  know  should
              have  6‐pica  margins  left and right, it makes sense to enter a
              left and right margin, like this:
                     .L_MARGIN 6P
                     .R_MARGIN 6P

              That way, you don’t have to worry  about  calculating  the  line
              length.   On  the  other hand, if you know the line length for a
              patch of type should be 17 picas and 3 points, entering the line
              length with LL is much easier than calculating the right margin,
              e.g.,
                     .LL 17P+3p

              If you use the macros .PAGE, .PAGEWIDTH or PAPER without  invok‐
              ing  .R_MARGIN  afterward, mom automatically sets .R_MARGIN to 1
              inch.  If you set a line length after these macros  (with  .LL),
              the  line length calculated by .R_MARGIN is, of course, overrid‐
              den.

              Note: .R_MARGIN behaves in a special way when you’re  using  the
              document processing macros.

       .ST <tab number> L | R | C | J [ QUAD ]

              After  string  tabs  have  been marked off on an input line (see
              \*[ST]...\*[STX]), you need to set them by giving them a  direc‐
              tion and, optionally, the QUAD argument.

              In this respect, .ST is like .TAB_SET except that you don’t have
              to  give  .ST  an  indent or a line length (that’s already taken
              care of, inline, by \*[ST]...\*[STX]).

              If you want string tab 1 to be left, enter
                     .ST 1 L
              If you want it to be left and filled, enter
                     .ST 1 L QUAD
              If you want it to be justified, enter
                     .ST 1 J

       .TAB <tab number>
              After tabs have been defined (either with .TAB_SET or .ST), .TAB
              moves to whatever tab number you pass it as an argument.

              For example,
                     .TAB 3
              moves you to tab 3.

              Note: .TAB breaks the line preceding it  and  advances  1  line‐
              space.  Hence,
                     .TAB 1
                     A line of text in tab 1.
                     .TAB 2
                     A line of text in tab 2.
              produces, on output
                     A line of text in tab 1.
                                                  A line of text in tab 2.

              If  you  want the tabs to line up, use .TN (“Tab Next”) or, more
              conveniently, the inline escape sequence \*[TB+]:
                     .TAB 1
                     A line of text in tab 1.\*[TB+]
                     A line of text in tab 2.
              which produces
                     A line of text in tab 1.   A line of text in tab 2.

              If the text in your tabs runs to several lines, and you want the
              first lines of each tab to align, you must use the  multi‐column
              macros.

              Additional  note:  Any  indents in effect prior to calling a tab
              are automatically turned off by TAB.  If you were  happily  zip‐
              ping  down the page with a left indent of 2 picas turned on, and
              you call a tab whose indent from the left  margin  is  6  picas,
              your  new distance from the left margin will be 6 picas, not I 6
              picas plus the 2 pica indent.

              Tabs are not by nature columnar, which is to  say  that  if  the
              text  inside  a  tab  runs to several lines, calling another tab
              does not automatically move to the baseline of the first line in
              the previous tab.  To demonstrate:
                     TAB 1
                     Carrots
                     Potatoes
                     Broccoli
                     .TAB 2
                     $1.99/5 lbs
                     $0.25/lb
                     $0.99/bunch
              produces, on output
                     Carrots
                     Potatoes
                     Broccoli
                                 $1.99/5 lbs
                                 $0.25/lb
                                 $0.99/bunch

       .TB <tab number>
              Alias to .TAB

       .TI [ <measure> ]
              Temporary left indent — the optional argument requires a unit of
              measure

              A temporary indent is one that applies only to the first line of
              text that comes after it.  Its chief use is indenting the  first
              line  of paragraphs.  (Mom’s .PP macro, for example, uses a tem‐
              porary indent.)

              The first time you invoke .TI, you must give it a  measure.   If
              you want to indent the first line of a paragraph by, say, 2 ems,
              do
                     .TI 2m

              Subsequent  invocations  of  .TI  do not require you to supply a
              measure; mom keeps track of the last measure you gave it.

              Because temporary indents are temporary, there’s no need to turn
              them off.

              IMPORTANT: Unlike .IL, .IR and IB, measures given to .TI are NOT
              additive.  In the following example, the second ".TI 2P" is  ex‐
              actly 2 picas.
                     .TI 1P
                     The beginning of a paragraph...
                     .TI 2P
                     The beginning of another paragraph...

       .TN    Tab Next

              Inline escape \*[TB+]

              TN  moves  over  to  the  next tab in numeric sequence (tab n+1)
              without advancing on the page.  See the NOTE in the  description
              of the .TAB macro for an example of how TN works.

              In  tabs that aren’t given the QUAD argument when they’re set up
              with .TAB_SET or ST, you must terminate the line  preceding  .TN
              with the \c inline escape sequence.  Conversely, if you did give
              a QUAD argument to .TAB_SET or ST, the \c must not be used.

              If you find remembering whether to put in the \c bothersome, you
              may prefer to use the inline escape alternative to .TN, \*[TB+],
              which works consistently regardless of the fill mode.

              Note: You must put text in the input line immediately after .TN.
              Stacking of .TN’s is not allowed.  In other words, you cannot do
                     .TAB 1
                     Some text\c
                     .TN
                     Some more text\c
                     .TN
                     .TN
                     Yet more text
              The above example, assuming tabs numbered from 1 to 4, should be
              entered
                     .TAB 1
                     Some text\c
                     .TN
                     Some more text\c
                     .TN
                     \&\c
                     .TN
                     Yet more text
              \& is a zero‐width, non‐printing character that groff recognizes
              as  valid input, hence meets the requirement for input text fol‐
              lowing .TN.

       .TQ    TQ takes you out of whatever tab you were in, advances  1  line‐
              space, and restores the left margin, line length, quad direction
              and fill mode that were in effect prior to invoking any tabs.

       .T_MARGIN <top margin>
              Top margin

              Requires a unit of measure

              .T_MARGIN  establishes  the distance from the top of the printer
              sheet at which you want your type to start.  It requires a  unit
              of  measure,  and  decimal  fractions are allowed.  To set a top
              margin of 2½ centimetres, you’d enter
                     .T_MARGIN 2.5c
              .T_MARGIN calculates the vertical position of the first line  of
              type  on a page by treating the top edge of the printer sheet as
              a baseline.  Therefore,
                     .T_MARGIN 1.5i
              puts the baseline of the first line of type  1½  inches  beneath
              the top of the page.

              Note:  .T_MARGIN  means something slightly different when you’re
              using the document processing macros.  See Top and  bottom  mar‐
              gins in document processing for an explanation.

              IMPORTANT:  .T_MARGIN  does  two  things: it establishes the top
              margin for pages that come after it and it moves to  that  posi‐
              tion  on  the current page.  Therefore, .T_MARGIN should only be
              used at the top of a file (prior to entering text) or after NEW‐
              PAGE, like this:
                     .NEWPAGE
                     .T_MARGIN 6P
                     <text>

Authors
       mom was written by Peter Schaffter ⟨peter@schaffter.ca⟩.   PDF  support
       was  provided by Deri James ⟨deri@chuzzlewit.myzen.co.uk⟩.  This manual
       page was written by Bernd Warken.

See also
       /usr/share/doc/groff-1.23.0/html/mom/toc.html
              entry point to the HTML documentation

       ⟨http://www.schaffter.ca/mom/momdoc/toc.html⟩
              HTML documentation online

       ⟨http://www.schaffter.ca/mom/⟩
              the mom macros homepage

       Groff: The GNU Implementation of troff, by Trent A. Fisher  and  Werner
       Lemberg,  is the primary groff manual.  You can browse it interactively
       with “info groff”.

       pdfmom(1), groff(1), troff(1)

groff 1.23.0                      2 July 2023                     groff_mom(7)
───────────────────────────────────────────────────────────────────────────────
groff_ms(7)            Miscellaneous Information Manual            groff_ms(7)

Name
       groff_ms - GNU roff manuscript macro package for formatting documents

Synopsis
       groff -ms [option ...] [file ...]
       groff -m ms [option ...] [file ...]

Description
       The GNU implementation of the ms macro package is  part  of  the  groff
       document  formatting system.  The ms package is suitable for the compo‐
       sition of letters, memoranda, reports, and books.

       These groff macros support cover page and table of contents generation,
       automatically numbered headings, several paragraph styles, a variety of
       text styling options, footnotes, and  multi‐column  page  layouts.   ms
       supports the tbl(1), eqn(1), pic(1), and refer(1) preprocessors for in‐
       clusion  of  tables, mathematical equations, diagrams, and standardized
       bibliographic citations.

       This implementation is mostly compatible with the documented  interface
       and  behavior  of  AT&T Unix Version 7 ms.  Many extensions from 4.2BSD
       (Berkeley) and Tenth Edition Research Unix have been recreated.

Usage
       The ms macro package expects a certain amount  of  structure:  a  well‐
       formed  document  contains  at  least one paragraphing or heading macro
       call.  To compose a simple document from scratch, begin it  by  calling
       .LP or .PP.  Longer documents have a structure as follows.

       Document type
              Calling  the RP macro at the beginning of your document puts the
              document description (see below) on a cover page.  Otherwise, ms
              places this information on the first page, followed  immediately
              by  the body text.  Some document types found in other ms imple‐
              mentations are specific to AT&T or Berkeley, and  are  not  sup‐
              ported in groff ms.

       Format and layout
              By  setting  registers and strings, you can configure your docu‐
              ment’s typeface, margins,  spacing,  headers  and  footers,  and
              footnote  arrangement.   See  subsection  “Document control set‐
              tings” below.

       Document description
              A document description consists of any of: a title, one or  more
              authors’  names  and affiliated institutions, an abstract, and a
              date or other identifier.  See subsection “Document  description
              macros” below.

       Body text
              The  main  matter  of  your document follows its description (if
              any).  ms supports highly structured text  consisting  of  para‐
              graphs  interspersed  with  multi‐level headings (chapters, sec‐
              tions, subsections, and so forth) and augmented by lists,  foot‐
              notes,  tables,  diagrams, and similar material.  The preponder‐
              ance of subsections below covers these matters.

       Table of contents
              Macros enable the collection of entries for a table of  contents
              (or index) as the material they discuss appears in the document.
              You  then  call a macro to emit the table of contents at the end
              of your document.  The table of contents must necessarily follow
              the rest of the text since GNU troff is a single‐pass formatter;
              it thus cannot determine the page number of a  division  of  the
              text  until it has been set and output.  Since ms output was de‐
              signed for the production of hard copy, the  traditional  proce‐
              dure  was to manually relocate the pages containing the table of
              contents between the cover page and the body text.  Today,  page
              resequencing is more often done in the digital domain.  An index
              works similarly, but because it typically needs to be sorted af‐
              ter collection, its preparation requires separate processing.

   Document control settings
       The  following tables list the document control registers, strings, and
       special characters.  For any parameter whose default is unsatisfactory,
       define it before calling any ms macro other than RP.

                                   Margin settings
       Parameter            Definition               Effective       Default
       ────────────────────────────────────────────────────────────────────────
       \n[PO]      Page offset (left margin)       next page        1i (0)
       \n[LL]      Line length                     next paragraph   6.5i (65n)
       \n[LT]      Title line length               next paragraph   6.5i (65n)
       \n[HM]      Top (header) margin             next page        1i
       \n[FM]      Bottom (footer) margin          next page        1i
       ────────────────────────────────────────────────────────────────────────

                              Titles (headers, footers)
       Parameter               Definition                 Effective    Default
       ────────────────────────────────────────────────────────────────────────
       \*[LH]      Left header text                      next header   empty
       \*[CH]      Center header text                    next header   -\n[%]-
       \*[RH]      Right header text                     next header   empty
       \*[LF]      Left footer text                      next footer   empty
       \*[CF]      Center footer text                    next footer   empty
       \*[RF]      Right footer text                     next footer   empty
       ────────────────────────────────────────────────────────────────────────

                                    Text settings
       Parameter              Definition                Effective      Default
       ────────────────────────────────────────────────────────────────────────
       \n[PS]      Point size                         next paragraph   10p
       \n[VS]      Vertical spacing (leading)         next paragraph   12p
       \n[HY]      Hyphenation mode                   next paragraph   6
       \*[FAM]     Font family                        next paragraph   T
       ────────────────────────────────────────────────────────────────────────

                                 Paragraph settings
        Parameter             Definition              Effective       Default
       ────────────────────────────────────────────────────────────────────────
       \n[PI]        Indentation                    next paragraph   5n
       \n[PD]        Paragraph distance (spacing)   next paragraph   0.3v (1v)
       \n[QI]        Quotation indentation          next paragraph   5n
       \n[PORPHANS]  # of initial lines kept        next paragraph   1
       ────────────────────────────────────────────────────────────────────────

                                  Heading settings
        Parameter              Definition             Effective      Default
       ────────────────────────────────────────────────────────────────────────
       \n[PSINCR]     Point size increment           next heading   1p
       \n[GROWPS]     Size increase depth limit      next heading   0
       \n[HORPHANS]   # of following lines kept      next heading   1
       \*[SN-STYLE]   Numbering style (alias)        next heading   \*[SN-DOT]
       ────────────────────────────────────────────────────────────────────────

       \*[SN-STYLE] can alternatively be made an alias of  \*[SN-NO-DOT]  with
       the als request.

                                  Footnote settings
       Parameter             Definition               Effective      Default
       ────────────────────────────────────────────────────────────────────────
       \n[FI]      Indentation                      next footnote   2n
       \n[FF]      Format                           next footnote   0
       \n[FPS]     Point size                       next footnote   \n[PS]-2p
       \n[FVS]     Vertical spacing (leading)       next footnote   \n[FPS]+2p
       \n[FPD]     Paragraph distance (spacing)     next footnote   \n[PD]/2
       \*[FR]      Line length ratio                special         11/12
       ────────────────────────────────────────────────────────────────────────

                                  Display settings
       Parameter               Definition                Effective    Default
       ────────────────────────────────────────────────────────────────────────
       \n[DD]      Display distance (spacing)            special     0.5v (1v)
       \n[DI]      Display indentation                   special     0.5i
       ────────────────────────────────────────────────────────────────────────

                                   Other settings
         Parameter               Definition              Effective     Default
       ────────────────────────────────────────────────────────────────────────
       \n[MINGW]       Minimum gutter width             next page      2n
       \n[TC-MARGIN]   TOC page number margin width     next PX call   \w'000'
       \[TC-LEADER]    TOC leader character             next PX call   .\h'1m'
       ────────────────────────────────────────────────────────────────────────

       For entries marked “special” in the “Effective” column, see the discus‐
       sion  in the applicable section below.  The PO, LL, and LT register de‐
       faults vary by output device and paper format; the values shown are for
       typesetters using U.S. letter paper, and then terminals.   See  section
       “Paper  format”  of  groff(1).   The PD and DD registers use the larger
       value if the vertical motion quantum of the output device is too coarse
       for the smaller one; usually, this is the case only for output to  ter‐
       minals  and  emulators  thereof.  The “gutter” affected by \n[MINGW] is
       the gap between columns  in  multiple‐column  page  arrangements.   The
       TC-MARGIN  register  and TC-LEADER special character affect the format‐
       ting of tables of contents assembled by the XS, XA, and XE macros.

   Document description macros
       Define information describing the document by calling the macros  below
       in  the  order shown; .DA or .ND can be called to set the document date
       (or other identifier) at any time before (a) the abstract, if  present,
       or (b) its information is required in a header or footer.  Use of these
       macros  is  optional,  except that .TL is mandatory if any of .RP, .AU,
       .AI, or .AB is called, and .AE is mandatory if .AB is called.

       .RP [no-repeat-info] [no-renumber]
              Use the “report” (AT&T: “released paper”) format for your  docu‐
              ment,  creating  a separate cover page.  The default arrangement
              is to place most of  the  document  description  (title,  author
              names  and  institutions, and abstract, but not the date) at the
              top of the first page.  If the optional no-repeat-info  argument
              is  given,  ms  produces a cover page but does not repeat any of
              its information on subsequently (but see the DA macro below  re‐
              garding the date).  Normally, .RP sets the page number following
              the  cover page to 1.  Specifying the optional no-renumber argu‐
              ment suppresses this alteration.  Optional arguments  can  occur
              in any order.  “no” is recognized as a synonym of no-repeat-info
              for AT&T compatibility.

       .TL    Specify  the  document  title.   ms collects text on input lines
              following this call into the title until reaching .AU, .AB, or a
              heading or paragraphing macro call.

       .AU    Specify an author’s name.  ms collects text on input lines  fol‐
              lowing this call into the author’s name until reaching .AI, .AB,
              another  .AU,  or a heading or paragraphing macro call.  Call it
              repeatedly to specify multiple authors.

       .AI    Specify the preceding author’s institution.  An .AU call is use‐
              fully followed by at most one .AI call; if there are  more,  the
              last .AI call controls.  ms collects text on input lines follow‐
              ing  this call into the author’s institution until reaching .AU,
              .AB, or a heading or paragraphing macro call.

       .DA [x ...]
              Typeset the current date, or any  arguments  x,  in  the  center
              footer,  and,  if .RP is also called, left‐aligned at the end of
              the document description on the cover page.

       .ND [x ...]
              Typeset the current date, or any arguments x,  if  .RP  is  also
              called,  left‐aligned  at the end of the document description on
              the cover page.  This is groff ms’s default.

       .AB [no]
              Begin the abstract.  ms collects text on input  lines  following
              this  call into the abstract until reaching an .AE call.  By de‐
              fault, ms places the word “ABSTRACT”  centered  and  in  italics
              above the text of the abstract.  The optional argument “no” sup‐
              presses this heading.

       .AE    End the abstract.

   Text settings
       The  FAM  string,  a GNU extension, sets the font family for body text;
       the default is “T”.  The PS and VS registers set the type size and ver‐
       tical spacing (distance between  text  baselines),  respectively.   The
       font  family  and  type  size are ignored on terminal devices.  Setting
       these parameters before the first call of a heading,  paragraphing,  or
       (non‐date)  document  description  macro  also applies them to headers,
       footers, and (for FAM) footnotes.

       The HY register defines the automatic hyphenation mode used with the hy
       request.  Setting \n[HY] to 0 is equivalent to using  the  nh  request.
       This is a Tenth Edition Research Unix extension.

   Typographical symbols
       ms  provides  a  few strings to obtain typographical symbols not easily
       entered with the keyboard.  These and many others are available as spe‐
       cial character escape sequences—see groff_char(7).

       \*[-]  Interpolate an em dash.

       \*[Q]
       \*[U]  Interpolate typographer’s quotation marks where  available,  and
              neutral  double  quotes  otherwise.  \*[Q] is the left quote and
              \*[U] the right.

   Paragraphs
       Paragraphing macros break, or terminate, any  pending  output  line  so
       that a new paragraph can begin.  Several paragraph types are available,
       differing  in  how indentation applies to them: to left, right, or both
       margins; to the first output line of the paragraph, all  output  lines,
       or all but the first.  All paragraphing macro calls cause the insertion
       of  vertical  space  in the amount stored in the PD register, except at
       page or column breaks, or adjacent to displays.

       The PORPHANS register defines the minimum number of  initial  lines  of
       any paragraph that must be kept together to avoid isolated lines at the
       bottom of a page.  If a new paragraph is started close to the bottom of
       a  page,  and  there  is insufficient space to accommodate \n[PORPHANS]
       lines before an automatic page break, then a page break is  forced  be‐
       fore the start of the paragraph.  This is a GNU extension.

       .LP    Set a paragraph without any (additional) indentation.

       .PP    Set a paragraph with a first‐line left indentation in the amount
              stored in the PI register.

       .IP [marker [width]]
              Set a paragraph with a left indentation.  The optional marker is
              not  indented  and is empty by default.  width overrides the in‐
              dentation amount in \n[PI]; its default unit is “n”.  Once spec‐
              ified, width applies to further .IP calls until specified  again
              or a heading or different paragraphing macro is called.

       .QP    Set  a  paragraph  indented  from both left and right margins by
              \n[QI].

       .QS
       .QE    Begin (QS) and end (QE) a region where  each  paragraph  is  in‐
              dented  from  both  margins by \n[QI].  The text between .QS and
              .QE can be structured  further  by  use  of  other  paragraphing
              macros.

       .XP    Set  an  “exdented”  paragraph—one  with  a  left indentation of
              \n[PI] on every line except the first (also known as  a  hanging
              indent).  This is a Berkeley extension.

   Headings
       Use headings to create a hierarchical structure for your document.  The
       ms macros print headings in bold using the same font family and, by de‐
       fault,  type  size  as  the body text.  Headings are available with and
       without automatic numbering.  Text on input lines following  the  macro
       call becomes the heading’s title.  Call a paragraphing macro to end the
       heading text and start the section’s content.

       .NH [depth]
              Set  an  automatically numbered heading.  ms produces a numbered
              heading in the form a.b.c..., to any  level  desired,  with  the
              numbering of each depth increasing automatically and being reset
              to  zero when a more significant depth is increased.  “1” is the
              most significant or coarsest division  of  the  document.   Only
              non‐zero values are output.  If depth is omitted, it is taken to
              be  1.   If  you specify depth such that an ascending gap occurs
              relative to the previous NH call—that is, you “skip a depth”, as
              by “.NH 1” and then “.NH 3”, groff ms emits  a  warning  on  the
              standard error stream.

       .NH S heading‐depth‐index ...
              Alternatively, you can give NH a first argument of “S”, followed
              by  integers  to  number the heading depths explicitly.  Further
              automatic numbering, if used, resumes using  the  specified  in‐
              dices  as their predecessors.  This feature is a Berkeley exten‐
              sion.

       After .NH is called, the assigned  number  is  made  available  in  the
       strings SN-DOT (as it appears in a printed heading with default format‐
       ting,  followed by a terminating period) and SN-NO-DOT (with the termi‐
       nating period omitted).  These are GNU extensions.

       You can control the style used to print numbered headings  by  defining
       an appropriate alias for the string SN-STYLE.  By default, \*[SN-STYLE]
       is aliased to \*[SN-DOT].  If you prefer to omit the terminating period
       from  numbers  appearing  in  numbered  headings,  you  may alias it to
       \*[SN-NO-DOT].  Any such change in numbering  style  becomes  effective
       from  the  next  use  of  .NH  following  redefinition of the alias for
       \*[SN-STYLE].  The formatted number of the current heading is available
       in \*[SN] (a feature first documented by Berkeley); this string facili‐
       tates its inclusion in, for example, table captions,  equation  labels,
       and .XS/.XA/.XE table of contents entries.

       .SH [depth]
              Set an unnumbered heading.  The optional depth argument is a GNU
              extension  indicating  the  heading  depth  corresponding to the
              depth argument of .NH.  It matches the type size  at  which  the
              heading  is  set to that of a numbered heading at the same depth
              when the \n[GROWPS] and \n[PSINCR] heading size adjustment mech‐
              anism is in effect.

       The PSINCR register defines an increment in type size to be applied  to
       a  heading  at  a  lesser depth than that specified in \n[GROWPS].  The
       value of \n[PSINCR] should be specified in points with the “p”  scaling
       unit and may include a fractional component.

       The GROWPS register defines the heading depth above which the type size
       increment  set by \n[PSINCR] becomes effective.  For each heading depth
       less than the value of  \n[GROWPS],  the  type  size  is  increased  by
       \n[PSINCR].  Setting \n[GROWPS] to a value less than 2 disables the in‐
       cremental heading size feature.

       In  other  words,  if  the value of GROWPS register is greater than the
       depth argument to a .NH or .SH call, the type size of  a  heading  pro‐
       duced  by these macros increases by \n[PSINCR] units over \n[PS] multi‐
       plied by the difference of \n[GROWPS] and depth.

       The \n[HORPHANS] register operates in conjunction with the  NH  and  SH
       macros  to inhibit the printing of isolated headings at the bottom of a
       page; it specifies the minimum number of lines of the subsequent  para‐
       graph  that  must be kept on the same page as the heading.  If insuffi‐
       cient space remains on the current page to accommodate the heading  and
       this  number  of lines of paragraph text, a page break is forced before
       the heading is printed.  Any display macro call or tbl, pic, or eqn re‐
       gion between the heading and the subsequent paragraph  suppresses  this
       grouping.

   Typeface and decoration
       The  ms macros provide a variety of ways to style text.  Attend closely
       to the ordering of arguments labeled pre and post, which is  not  intu‐
       itive.  Support for pre arguments is a GNU extension.

       .B [text [post [pre]]]
              Style  text in bold, followed by post in the previous font style
              without intervening space, and preceded by pre similarly.  With‐
              out arguments, ms styles subsequent text in bold until the  next
              paragraphing, heading, or no‐argument typeface macro call.

       .R [text [post [pre]]]
              As  .B,  but use the roman style (upright text of normal weight)
              instead of bold.  Argument recognition is a GNU extension.

       .I [text [post [pre]]]
              As .B, but use an italic or oblique style instead of bold.

       .BI [text [post [pre]]]
              As .B, but use a bold italic or bold oblique  style  instead  of
              upright bold.  This is a Tenth Edition Research Unix extension.

       .CW [text [post [pre]]]
              As  .B, but use a constant‐width (monospaced) roman typeface in‐
              stead of bold.  This is a Tenth Edition Research Unix extension.

       .BX [text]
              Typeset text and draw a box around it.  On terminal devices, re‐
              verse video is used instead.  If you want text to contain space,
              use unbreakable space or horizontal motion escape sequences (\~,
              \space, \^, \|, \0, or \h).

       .UL [text [post]]
              Typeset text with an underline.  post, if present, is set  after
              text with no intervening space.

       .LG    Set  subsequent  text  in  larger type (2 points larger than the
              current size) until the next type size, paragraphing, or heading
              macro call.  You can specify this macro multiple  times  to  en‐
              large the type size as needed.

       .SM    Set  subsequent  text in smaller type (2 points smaller than the
              current size) until the next type size, paragraphing, or heading
              macro call.  You can specify this macro multiple times to reduce
              the type size as needed.

       .NL    Set subsequent text at the normal type size (\n[PS]).

       When pre is used, a hyphenation control escape sequence \%  that  would
       ordinarily start text must start pre instead.

       groff  ms also offers strings to begin and end super‐ and subscripting.
       These are GNU extensions.

       \*{
       \*}    Begin and end superscripting, respectively.

       \*<
       \*>    Begin and end subscripting, respectively.

   Indented regions
       You may need to indent a region of text while otherwise  formatting  it
       normally.  Indented regions can be nested.

       .RS    Begin  a region where headings, paragraphs, and displays are in‐
              dented (further) by \n[PI].

       .RE    End the (next) most recent indented region.

   Keeps, boxed keeps, and displays
       On occasion, you may want to keep several lines of text, or a region of
       a document, together on a single page,  preventing  an  automatic  page
       break  within certain boundaries.  This can cause a page break to occur
       earlier than it normally would.

       You can alternatively specify a floating keep: if a keep cannot fit  on
       the  current  page, ms holds its contents and allows text following the
       keep (in the source document) to fill in the remainder of  the  current
       page.  When the page breaks, whether by reaching the end or bp request,
       ms puts the floating keep at the beginning of the next page.

       .KS    Begin a keep.

       .KF    Begin a floating keep.

       .KE    End (floating) keep.

       As  an  alternative to the keep mechanism, the ne request forces a page
       break if there is not at least the amount of vertical  space  specified
       in its argument remaining on the page.

       A boxed keep has a frame drawn around it.

       .B1    Begin a keep with a box drawn around it.

       .B2    End boxed keep.

       Boxed  keep  macros  cause  breaks; if you need to box a word or phrase
       within a line, see the BX macro in section “Highlighting”  above.   Box
       lines  are  drawn as close as possible to the text they enclose so that
       they are usable within paragraphs.  If you wish to place  one  or  more
       paragraphs in a boxed keep, you may improve their appearance by calling
       .B1 after the first paragraphing macro, and by adding a small amount of
       vertical space before calling .B2.

       If you want a boxed keep to float, you will need to enclose the .B1 and
       .B2 calls within a pair of .KF and .KE calls.

       Displays  turn  off  filling;  lines of verse or program code are shown
       with their lines broken as in the source document without requiring  br
       requests  between  lines.  Displays can be kept on a single page or al‐
       lowed to break across pages.  The DS macro begins a kept display of the
       layout specified in its first argument;  non‐kept  displays  are  begun
       with dedicated macros corresponding to their layout.

       .DS L
       .LD    Begin (DS: kept) left‐aligned display.

       .DS [I [indent]]
       .ID [indent]
              Begin (DS: kept) display indented by indent if specified, \n[DI]
              otherwise.

       .DS B
       .BD    Begin  (DS:  kept)  block  display:  the entire display is left‐
              aligned, but indented such that the longest line in the  display
              is centered on the page.

       .DS C
       .CD    Begin  (DS:  kept) centered display: each line in the display is
              centered.

       .DS R
       .RD    Begin (DS: kept) right‐aligned display.  This is  a  GNU  exten‐
              sion.

       .DE    End any display.

       The distance stored in \n[DD] is inserted before and after each pair of
       display  macros;  this is a Berkeley extension.  In groff ms, this dis‐
       tance replaces any  adjacent  inter‐paragraph  distance  or  subsequent
       spacing  prior  to  a section heading.  The DI register is a GNU exten‐
       sion; its value is an indentation applied to displays created with  .DS
       and  .ID without arguments, to “.DS I” without an indentation argument,
       and to equations set with “.EQ I”.  Changes to either register take ef‐
       fect at the next display boundary.

   Tables, figures, equations, and references
       The ms package is often used with the tbl, pic,  eqn,  and  refer  pre‐
       processors.  The \n[DD] distance is also applied to regions of the doc‐
       ument  preprocessed  with  eqn, pic, and tbl.  Mark text meant for pre‐
       processors by enclosing it in pairs of tokens as follows, with  nothing
       between  the dot and the macro name.  The preprocessors match these to‐
       kens only at the start of an input line.

       .TS [H]
       .TE    Demarcate a table to be processed by the tbl preprocessor.   The
              optional  H  argument  instructs  ms to repeat table rows (often
              column headings) at the top of each new page the table spans, if
              applicable; calling the TH macro marks the  end  of  such  rows.
              tbl(1)  provides  a  comprehensive reference to the preprocessor
              and offers examples of its use.

       .PS
       .PE
       .PF    .PS begins a picture to be processed by  the  pic  preprocessor;
              either  of  .PE or .PF ends it, the latter with “flyback” to the
              vertical position at its top.

       .EQ [align [label]]
       .EN    Demarcate an equation to be processed by the  eqn  preprocessor.
              The  equation is centered by default; align can be C, L, or I to
              (explicitly) center, left‐align, or indent it by \n[DI], respec‐
              tively.  If specified, label is set right‐aligned.

       .[
       .]     Demarcate a bibliographic citation to be processed by the  refer
              preprocessor.   refer(1)  provides  a comprehensive reference to
              the preprocessor and the format of its bibliographic database.

       When refer emits collected references (as might be  done  on  a  “Works
       Cited”  page),  it  interpolates the string \*[REFERENCES] as an unnum‐
       bered heading (.SH).

       Attempting to place a multi‐page table inside a keep can  lead  to  un‐
       pleasant results, particularly if the tbl “allbox” option is used.

   Footnotes
       A  footnote is typically anchored to a place in the text with a marker,
       which is a small integer, a symbol, or arbitrary user‐specified text.

       \**    Place an automatic number, an  automatically  generated  numeric
              footnote marker, in the text.  Each time this string is interpo‐
              lated, the number it produces increments by one.  Automatic num‐
              bers start at 1.  This is a Berkeley extension.

       Enclose  the  footnote  text  in FS and FE macro calls to set it at the
       nearest available “foot”, or bottom, of a text column or page.

       .FS [marker]
              Begin a footnote.  The .FS-MARK hook (see below) is called  with
              any  supplied  marker argument, which is then also placed at the
              beginning of the footnote text.  If marker is omitted, the  next
              pending  automatic  number  enqueued  by  interpolation of the *
              string is used, and if none exists, nothing is prefixed.

       .FE    End footnote text.

       groff ms provides a hook macro, FS-MARK, for user‐determined operations
       to be performed when the FS macro is called.  It is passed the same ar‐
       guments as .FS itself.  By default, this macro has an empty definition.
       .FS-MARK is a GNU extension.

       Footnote text is formatted as paragraphs are, using  analogous  parame‐
       ters.   The  registers  FI, FPD, FPS, and FVS correspond to PI, PD, PS,
       and VS, respectively; FPD, FPS, and FVS are GNU extensions.

       The FF register controls the formatting of automatically numbered foot‐
       note paragraphs, and those for which .FS is given a marker argument, at
       the bottom of a column or page as follows.

              0      Set an automatic number, or a specified FS  marker  argu‐
                     ment,  as  a  superscript (on typesetter devices) or sur‐
                     rounded by square brackets (on terminals).  The  footnote
                     paragraph  is indented as with .PP if there is an .FS ar‐
                     gument or an automatic number, and as with .LP otherwise.
                     This is the default.

              1      As 0, but set the marker as regular text, and  follow  an
                     automatic number with a period.

              2      As 1, but without indentation (like .LP).

              3      As  1,  but  set  the  footnote paragraph with the marker
                     hanging (like .IP).

   Language and localization
       groff ms provides several strings that you can customize for  your  own
       purposes,  or  redefine  to  adapt the macro package to languages other
       than English.  It is already localized for Czech, German, French, Ital‐
       ian, and Swedish.  Load the desired localization  macro  package  after
       ms; see groff_tmac(5).

                  String            Default
              ───────────────────────────────────
              \*[REFERENCES]   References
              \*[ABSTRACT]     \f[I]ABSTRACT\f[]
              \*[TOC]          Table of Contents
              \*[MONTH1]       January
              \*[MONTH2]       February
              \*[MONTH3]       March
              \*[MONTH4]       April
              \*[MONTH5]       May
              \*[MONTH6]       June
              \*[MONTH7]       July
              \*[MONTH8]       August
              \*[MONTH9]       September
              \*[MONTH10]      October
              \*[MONTH11]      November
              \*[MONTH12]      December
              ───────────────────────────────────
       The  default  for  ABSTRACT includes font selection escape sequences to
       set the word in italics.

   Headers and footers
       There are multiple ways to produce headers and footers.  One is to  de‐
       fine  the  strings  LH,  CH,  and RH to set the left, center, and right
       headers, respectively; and LF, CF, and RF to set the left, center,  and
       right  footers.   This approach suffices for documents that do not dis‐
       tinguish odd‐ and even‐numbered pages.

       Another method is to call macros that set headers or footers  for  odd‐
       or  even‐numbered  pages.   Each  such macro takes a delimited argument
       separating the left, center, and right header or footer texts from each
       other.  You can replace the neutral apostrophes (')  shown  below  with
       any character not appearing in the header or footer text.  These macros
       are Berkeley extensions.

       .OH 'left'center'right'
       .OF 'left'center'right'
       .EH 'left'center'right'
       .EF 'left'center'right'
              The  OH  and EH macros define headers for odd‐ (recto) and even‐
              numbered (verso) pages, respectively; the OF and EF  macros  de‐
              fine footers for them.

       With  either  method,  a percent sign % in header or footer text is re‐
       placed by the current page number.  By default, ms places no header  on
       a page numbered “1” (regardless of its number format).

       .P1    Typeset  the header even on page 1.  To be effective, this macro
              must be called before the header trap is sprung on any page num‐
              bered “1”.  This is a Berkeley extension.

       For even greater flexibility, ms permits  redefinition  of  the  macros
       called  when  the  page  header and footer traps are sprung.  PT (“page
       trap”) is called by ms when the header is to be written, and BT  (“bot‐
       tom trap”) when the footer is to be.  The groff page location trap that
       ms  sets up to format the header also calls the (normally undefined) HD
       macro after .PT; you can define .HD if you need  additional  processing
       after  setting  the  header.  The HD hook is a Berkeley extension.  Any
       such macros you (re)define must implement  any  desired  specialization
       for odd‐, even‐, or first numbered pages.

   Tab stops
       Use the ta request to set tab stops as needed.

       .TA    Reset  the  tab stops to the ms default (every 5 ens).  Redefine
              this macro to create a different set of default tab stops.

   Margins
       Control margins using the registers summarized in the “Margins” portion
       of the table in section “Document control settings” above.  There is no
       setting for the right margin; the combination of page offset \n[PO] and
       line length \n[LL] determines it.

   Multiple columns
       ms can set text in as many columns as reasonably fit on the page.   The
       following  macros force a page break if a multi‐column layout is active
       when they are called.  \n[MINGW] is the default minimum  gutter  width;
       it is a GNU extension.  When multiple columns are in use, keeps and the
       HORPHANS  and PORPHANS registers work with respect to column breaks in‐
       stead of page breaks.

       .1C    Arrange page text in a single column (the default).

       .2C    Arrange page text in two columns.

       .MC [column‐width [gutter‐width]]
              Arrange page text in multiple columns.  If you specify no  argu‐
              ments,  it  is  equivalent  to the 2C macro.  Otherwise, column‐
              width is the width of each column and gutter‐width is the  mini‐
              mum distance between columns.

   Creating a table of contents
       Define  an  entry  to appear in the table of contents by bracketing its
       text between calls to the XS and XE macros.  A typical  application  is
       to  call  them  immediately  after NH or SH and repeat the heading text
       within them.  The XA macro, used within .XS/.XE pairs,  supplements  an
       entry—for instance, when it requires multiple output lines, whether be‐
       cause  a heading is too long to fit or because style dictates that page
       numbers not be repeated.  You may wish to indent the text thus  wrapped
       to  correspond to its heading depth; this can be done in the entry text
       by prefixing it with tabs or horizontal motion escape sequences, or  by
       providing a second argument to the XA macro.  .XS and .XA automatically
       associate the page number where they are called with the text following
       them,  but they accept arguments to override this behavior.  At the end
       of the document, call TC or PX to emit the table of contents;  .TC  re‐
       sets  the page number to i (Roman numeral one), and then calls PX.  All
       of these macros are Berkeley extensions.

       .XS [page‐number]
       .XA [page‐number [indentation]]
       .XE    Begin, supplement, and end a table of contents entry.  Each  en‐
              try  is  associated with page‐number (otherwise the current page
              number); a page‐number of “no” prevents a leader and page number
              from being emitted for that entry.  Use of .XA within .XS/.XE is
              optional; it can be repeated.  If indentation is present, a sup‐
              plemental entry is indented by that amount; ens are  assumed  if
              no  unit  is indicated.  Text on input lines between .XS and .XE
              is stored for later recall by .PX.

       .PX [no]
              Switch to single‐column layout.  Unless “no” is specified,  cen‐
              ter  and  interpolate \*[TOC] in bold and two points larger than
              the body text.  Emit the table of contents entries.

       .TC [no]
              Set the page number to 1, the page number  format  to  lowercase
              Roman numerals, and call PX (with a “no” argument, if present).

       The remaining features in this subsection are GNU extensions.  groff ms
       obviates the need to repeat heading text after .XS calls.  Call .XN and
       .XH  after  .NH and .SH, respectively.  Text to be appended to the for‐
       matted section heading, but not to appear in the table of contents  en‐
       try, can follow these calls.

       .XN heading‐text
              Format heading‐text and create a corresponding table of contents
              entry;  the  indentation  is computed from the depth argument of
              the preceding NH call.

       .XH depth heading‐text
              As .XN, but use depth to determine the indentation.

       groff ms encourages customization of table of  contents  entry  produc‐
       tion.  (Re‐)define any of the following macros as desired.

       .XN-REPLACEMENT heading‐text
       .XH-REPLACEMENT depth heading‐text
              These  hook  macros  implement .XN and .XH, and call XN-INIT and
              XH-INIT, respectively, then call XH-UPDATE-TOC  with  the  argu‐
              ments given them.

       .XH-INIT
       .XN-INIT
              These hook macros do nothing by default.

       .XH-UPDATE-TOC depth heading‐text
              Bracket heading‐text with XS and XE calls, indenting it by 2 ens
              per level of depth beyond the first.

       You  can  customize  the style of the leader that bridges each table of
       contents entry with its page number; define the TC-LEADER special char‐
       acter by using the char request.  A typical  leader  combines  the  dot
       glyph  “.” with a horizontal motion escape sequence to spread the dots.
       The width of the page number field is stored in the TC-MARGIN register.

Differences from AT&T ms
       The groff ms macros are an independent reimplementation, using no  AT&T
       code.   Since  they  take  advantage of the extended features of groff,
       they cannot be used with AT&T troff.  groff ms  supports  features  de‐
       scribed  above  as Berkeley and Tenth Edition Research Unix extensions,
       and adds several of its own.

       •  The internals of groff ms differ from  the  internals  of  AT&T  ms.
          Documents that depend upon implementation details of AT&T ms may not
          format  properly  with  groff ms.  Such details include macros whose
          function was not documented in the AT&T ms manual (“Typing Documents
          on the UNIX System: Using the -ms Macros with Troff and  Nroff”,  M.
          E. Lesk, Bell Laboratories, 1978).

       •  The  error‐handling  policy  of groff ms is to detect and report er‐
          rors, rather than to ignore them silently.

       •  Tenth Edition Research Unix supported P1/P2 macros to  bracket  code
          examples; groff ms does not.

       •  groff  ms  does not work in GNU troff’s AT&T compatibility mode.  If
          loaded when that mode is enabled, it aborts processing with a  diag‐
          nostic message.

       •  Multiple line spacing is not supported.  Use a larger vertical spac‐
          ing instead.

       •  groff  ms uses the same header and footer defaults in both nroff and
          troff modes as AT&T ms does in troff mode; AT&T’s default  in  nroff
          mode  is to put the date, in U.S. traditional format (e.g., “January
          1, 2021”), in the center footer (the CF string).

       •  Many groff ms macros, including those for paragraphs, headings,  and
          displays,  cause  a reset of paragraph rendering parameters, and may
          change the indentation; they do so not by incrementing or decrement‐
          ing it, but by setting it absolutely.  This can cause  problems  for
          documents that define additional macros of their own that try to ma‐
          nipulate indentation.  Use .RS and .RE instead of the in request.

       •  AT&T ms interpreted the values of the registers PS and VS in points,
          and  did  not  support the use of scaling units with them.  groff ms
          interprets values of the registers PS, VS, FPS, and FVS, equal to or
          larger than 1,000 (one thousand)  as  decimal  fractions  multiplied
          by  1,000.   (Register  values  are converted to and stored as basic
          units.  See  “Measurements”  in  the  groff  Texinfo  manual  or  in
          groff(7)).   This  threshold  makes use of a scaling unit with these
          parameters practical for high‐resolution  devices  while  preserving
          backward  compatibility.  It also permits expression of non‐integral
          type sizes.  For example, “groff -rPS=10.5p” at the shell prompt  is
          equivalent  to  placing “.nr PS 10.5p” at the beginning of the docu‐
          ment.

       •  AT&T ms’s AU macro  supported  arguments  used  with  some  document
          types; groff ms does not.

       •  Right‐aligned  displays  are available.  The AT&T ms manual observes
          that “it is tempting to assume that “.DS R” will right adjust lines,
          but it doesn’t work”.  In groff ms, it does.

       •  To make groff ms use the default page offset (which  also  specifies
          the  left  margin),  the  PO  register must stay undefined until the
          first ms macro is called.  This implies that \n[PO]  should  not  be
          used  early in the document, unless it is changed also: accessing an
          undefined register automatically defines it.

       •  groff ms supports the PN register, but it is not necessary; you  can
          access  the  page  number via the usual % register and invoke the af
          request to assign a different format to it if desired.  (If you  re‐
          define  the ms PT macro and desire special treatment of certain page
          numbers—like “1”—you may need to handle  a  non‐Arabic  page  number
          format, as groff ms’s .PT does; see the macro package source.  groff
          ms aliases the PN register to %.)

       •  The  AT&T ms manual documents registers CW and GW as setting the de‐
          fault column width and “intercolumn gap”,  respectively,  and  which
          applied when .MC was called with fewer than two arguments.  groff ms
          instead  treats  .MC without arguments as synonymous with .2C; there
          is thus no occasion for a default column width  register.   Further,
          the  MINGW register and the second argument to .MC specify a minimum
          space between columns, not the fixed gutter width of AT&T ms.

       •  The AT&T ms manual did not document the QI  register;  Berkeley  and
          groff ms do.

       •  The  register GS is set to 1 by the groff ms macros, but is not used
          by the AT&T ms package.  Documents that need  to  determine  whether
          they  are  being  formatted  with groff ms or another implementation
          should test this register.

   Unix Version 7 macros not implemented by groff ms
       Several macros described in the Unix Version  7  ms  documentation  are
       unimplemented by groff ms because they are specific to the requirements
       of  documents  produced  internally by Bell Laboratories, some of which
       also require a glyph for the Bell System logo that groff does not  sup‐
       port.   These macros implemented several document type formats (EG, IM,
       MF, MR, TM, TR), were meaningful only in conjunction with  the  use  of
       certain  document  types  (AT,  CS,  CT, OK, SG), stored the postal ad‐
       dresses of Bell Labs sites (HO, IH, MH, PY, WH), or lacked a stable de‐
       finition over time (UX).

Legacy features
       groff ms retains some legacy features solely to support  formatting  of
       historical  documents;  contemporary  ones  should not use them because
       they can render poorly.  See groff_char(7) instead.

   AT&T ms accent mark strings
       AT&T ms defined accent mark strings as follows.

       String   Description
       ──────────────────────────────────────────────────────
       \*[']    Apply acute accent to subsequent glyph.
       \*[`]    Apply grave accent to subsequent glyph.
       \*[:]    Apply dieresis (umlaut) to subsequent glyph.
       \*[^]    Apply circumflex accent to subsequent glyph.
       \*[~]    Apply tilde accent to subsequent glyph.
       \*[C]    Apply caron to subsequent glyph.
       \*[,]    Apply cedilla to subsequent glyph.

   Berkeley ms accent mark and glyph strings
       Berkeley ms offered an AM macro; calling it redefined the  AT&T  accent
       mark strings (except for \*C), applied them to the preceding glyph, and
       defined additional strings, some for spacing glyphs.

       .AM    Enable alternative accent mark and glyph‐producing strings.

       String   Description
       ───────────────────────────────────────────────────────────────
       \*[']    Apply acute accent to preceding glyph.
       \*[`]    Apply grave accent to preceding glyph.
       \*[:]    Apply dieresis (umlaut) to preceding glyph.
       \*[^]    Apply circumflex accent to preceding glyph.
       \*[~]    Apply tilde accent to preceding glyph.
       \*[,]    Apply cedilla to preceding glyph.
       \*[/]    Apply stroke (slash) to preceding glyph.
       \*[v]    Apply caron to preceding glyph.
       \*[_]    Apply macron to preceding glyph.
       \*[.]    Apply underdot to preceding glyph.
       \*[o]    Apply ring accent to preceding glyph.
       ───────────────────────────────────────────────────────────────
       \*[?]    Interpolate inverted question mark.
       \*[!]    Interpolate inverted exclamation mark.
       \*[8]    Interpolate small letter sharp s.
       \*[q]    Interpolate small letter o with hook accent (ogonek).
       \*[3]    Interpolate small letter yogh.
       \*[d‐]   Interpolate small letter eth.
       \*[D‐]   Interpolate capital letter eth.
       \*[th]   Interpolate small letter thorn.
       \*[TH]   Interpolate capital letter thorn.
       \*[ae]   Interpolate small ae ligature.
       \*[AE]   Interpolate capital ae ligature.
       \*[oe]   Interpolate small oe ligature.
       \*[OE]   Interpolate capital oe ligature.

Naming conventions
       The  following  conventions  are used for names of macros, strings, and
       registers.  External names available to documents that use the groff ms
       macros contain only uppercase letters and digits.

       Internally, the macros are divided into modules.  Conventions for iden‐
       tifier names are as follows.

       •  Names used only within one module are of the form module*name.

       •  Names used outside the module in which they are defined are  of  the
          form module@name.

       •  Names  associated  with  a  particular  environment  are of the form
          environment:name; these are used only within the par module.

       •  name does not have a module prefix.

       •  Constructed  names  used  to  implement  arrays  are  of  the   form
          array!index.

       Thus the groff ms macros reserve the following names:

       •  Names containing the characters *, @, and :.

       •  Names containing only uppercase letters and digits.

Files
       /usr/share/groff/1.23.0/tmac/s.tmac
              implements the package.

       /usr/share/groff/1.23.0/tmac/refer-ms.tmac
              implements refer(1) support for ms.

       /usr/share/groff/1.23.0/tmac/ms.tmac
              is  a  wrapper  enabling the package to be loaded with “groff -m
              ms”.

Authors
       The GNU version of the ms macro package was written by James Clark  and
       contributors.   This  document  was  written  by  Clark,  Larry  Kollar
       ⟨lkollar@despammed.com⟩, and G. Branden  Robinson  ⟨g.branden.robinson@
       gmail.com⟩.

See also
       A  manual is available in source and rendered form.  On your system, it
       may be compressed and/or available in additional formats.

       /usr/share/doc/groff-1.23.0/ms.ms
       /usr/share/doc/groff-1.23.0/ms.ps
              “Using groff with  the  ms  Macro  Package”;  Larry  Kollar  and
              G. Branden Robinson.

       /usr/share/doc/groff-1.23.0/msboxes.ms
       /usr/share/doc/groff-1.23.0/msboxes.pdf
              “Using  PDF  boxes  with  groff  and the ms macros”; Deri James.
              BOXSTART and BOXSTOP macros are available via the sboxes  exten‐
              sion package, enabling colored, bordered boxes when the pdf out‐
              put device is used.

       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       groff(1), troff(1), tbl(1), pic(1), eqn(1), refer(1)

groff 1.23.0                      2 July 2023                      groff_ms(7)
───────────────────────────────────────────────────────────────────────────────
groff_rfc1345(7)       Miscellaneous Information Manual       groff_rfc1345(7)

Name
       groff_rfc1345 - special character names from RFC 1345 and Vim digraphs

Description
       The  file  rfc1345.tmac  defines special character escape sequences for
       groff(7) based on the glyph mnemonics specified in RFC 1345 and the di‐
       graph table of the text editor Vim.  Each escape sequence translates to
       a Unicode code point, and will render correctly if the underlying  font
       is a Unicode font that covers the code point.

       For example, “\[Rx]” is the “recipe” or “prescription take” symbol, and
       maps  to the code point U+211E.  groff lets you write it as “\[u211E]”,
       but “\[Rx]” is more mnemonic.

       For  a  list  of  the  glyph  names  provided,  please  see  the   file
       rfc1345.tmac, which contains definitions of the form
              .char \[Rx] \[u211E]    \" PRESCRIPTION TAKE
       where  .char’s  first argument defines a groff special character escape
       sequence with a mnemonic glyph name, its second argument is  a  special
       character  escape sequence based on the code point, and the comment de‐
       scribes the glyph defined.

       The RFC 1345 glyph names cover a wide range of Unicode code points, in‐
       cluding supplemental Latin, Greek, Cyrillic, Hebrew, Arabic,  Hiragana,
       Katakana,  and  Bopomofo  letters, punctuation, math notation, currency
       symbols, industrial and entertainment icons, and box‐drawing symbols.

       The Vim digraph table is practically a subset of RFC 1345  (being  lim‐
       ited  to two‐character mnemonics), but, as a newer implementation, adds
       four mnemonics not specified in the RFC (the horizontal  ellipsis,  the
       Euro sign, and two mappings for the rouble sign).  These have also been
       added to rfc1345.tmac.

       rfc1345.tmac contains a total of 1,696 glyph names.  It is not an error
       to load rfc1345.tmac if your font does not have all the glyphs, as long
       as it contains the glyphs that you actually use in your document.

       The  RFC 1345 mnemonics are not identical in every case to the mappings
       for special character glyph names that are built in to groff; for exam‐
       ple, “\[<<]” means the “much less than” sign (U+226A) when rfc1345.tmac
       is not loaded and this special character is not otherwise defined by  a
       document  or  macro  package.   rfc1345.tmac  redefines  “\[<<]” to the
       “left‐pointing   double   angle   quotation   mark”   (U+00AB).     See
       groff_char(7)  for the full list of predefined special character escape
       sequences.

   Usage
       Load the rfc1345.tmac file.  This can be done by  either  adding  “.mso
       rfc1345.tmac” to your document before the first use of any of the glyph
       names  the  macro  file  defines,  or  by using the troff(1) option “-m
       rfc1345” from the shell.

   Bugs
       As the groff Texinfo manual notes, “[o]nly the current font is  checked
       for  ligatures  and  kerns;  neither special fonts nor entities defined
       with the char request (and its siblings) are taken into account.”  Many
       of the characters defined in rfc1345.tmac are accented  Latin  letters,
       and  will  be  affected by this deficiency, producing subpar typography
       ⟨https://savannah.gnu.org/bugs/?59932⟩.

Files
       /usr/share/groff/1.23.0/tmac/rfc1345.tmac
              implements the character mappings.

Authors
       rfc1345.tmac was contributed by Dorai Sitaram ⟨ds26gte@yahoo.com⟩.

See also
       RFC 1345 ⟨https://tools.ietf.org/html/rfc1345⟩, by Keld Simonsen,  June
       1992.

       The  Vim  digraph  table  can be listed using the vim(1) command “:help
       digraph-table”.

       groff_char(7)

groff 1.23.0                      2 July 2023                 groff_rfc1345(7)
───────────────────────────────────────────────────────────────────────────────
groff_trace(7)         Miscellaneous Information Manual         groff_trace(7)

Name
       groff_trace - macros for debugging GNU roff documents

Synopsis
       groff -m trace [option ...] [file ...]

Description
       trace is a macro package for the groff(7) document  formatting  system,
       designed as an aid for debugging documents written in its language.  It
       issues  a  message  to the standard error stream upon entry to and exit
       from each macro call.  This can ease the process of isolating errors in
       macro definitions.

       Activate the package by specifying the command‐line option  “-m  trace”
       to  the formatter program (often groff(1)).  You can achieve finer con‐
       trol by including the macro file within the document;  invoke  the  mso
       request,  as  in “.mso trace.tmac”.  Only macros that are defined after
       this invocation are traced.  If the trace-full register  is  set  to  a
       true value, as with the command‐line option “-r trace-full=1”, register
       and  string  assignments,  along  with  some other requests, are traced
       also.  If another macro package should be traced as  well,  specify  it
       after “-m trace” on the command line.

       The  macro  file  trace.tmac is unusual because it does not contain any
       macros to be called by a user.  Instead, groff’s macro  definition  and
       alteration  facilities  are  wrapped  such that they display diagnostic
       messages.

   Limitations
       Because trace.tmac wraps the de request (and its cousins), macro  argu‐
       ments are expanded one level more.  This causes problems if an argument
       uses  four or more backslashes to delay interpretation of an escape se‐
       quence.  For example, the macro call
              .foo \\\\n[bar]
       normally passes “\\n[bar]” to macro “foo”, but with  de  redefined,  it
       passes “\n[bar]” instead.

       The  solution  to this problem is to use groff’s \E escape sequence, an
       escape character that is not interpreted in copy mode.
              .foo \En[bar]

Examples
       We will illustrate trace.tmac using the shell’s “here document” feature
       to supply groff with a document on the standard input stream.  Since we
       are interested only in diagnostic messages appearing  on  the  standard
       error  stream, we discard the formatted output by redirecting the stan‐
       dard output stream to /dev/null.

   Observing nested macro calls
       Macro calls can be nested,  even  with  themselves.   Tracing  recurses
       along with them; this feature can help to detangle complex call stacks.

              $ cat <<EOF | groff -m trace > /dev/null
              .de countdown
              . nop \\$1
              . nr count (\\$1 ‐ 1)
              . if \\n[count] .countdown \\n[count]
              ..
              .countdown 3
              blastoff
              EOF
               *** .de countdown
               *** de trace enter: .countdown "3"
                *** de trace enter: .countdown "2"
                 *** de trace enter: .countdown "1"
                 *** trace exit: .countdown "1"
                *** trace exit: .countdown "2"
               *** trace exit: .countdown "3"

   Tracing with the mso request
       Now  let  us  activate tracing within the document, not with a command‐
       line option.  We might do this when using a macro package  like  ms  or
       mom,  where  we  may  not  want to be distracted by traces of macros we
       didn’t write.

              $ cat <<EOF | groff ‐ms > /dev/null
              .LP
              This is my introductory paragraph.
              .mso trace.tmac
              .de Mymac
              ..
              .Mymac
              .PP
              Let us review the existing literature.
              EOF
               *** .de Mymac
               *** de trace enter: .Mymac
               *** trace exit: .Mymac

       As tracing was not yet active when the macros “LP” and  “PP”  were  de‐
       fined (by s.tmac), their calls were not traced; contrast with the macro
       “Mymac”.

Files
       /usr/share/groff/1.23.0/tmac/trace.tmac
              implements the package.

Authors
       trace.tmac  was  written  by James Clark.  This document was written by
       Bernd Warken ⟨groff-bernd.warken-72@web.de⟩  and  G.  Branden  Robinson
       ⟨g.branden.robinson@gmail.com⟩.

See also
       Groff:  The  GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  You can browse it  interactively
       with “info groff”.

       groff(1)
              gives an overview of the groff document formatting system.

       troff(1)
              supplies details of the -m command‐line option.

       groff_tmac(5)
              offers a survey of groff macro packages.

       groff(7)
              is a reference manual for the groff language.

groff 1.23.0                      2 July 2023                   groff_trace(7)
───────────────────────────────────────────────────────────────────────────────
groff_www(7)           Miscellaneous Information Manual           groff_www(7)

Name
       groff_www - GNU roff macros for authoring web pages

Synopsis
       groff -m www [option ...] [file ...]

Description
       This  manual page describes the GNU www macro package, which is part of
       the groff(7) document formatting system.  This macro file is  automati‐
       cally  loaded  by  the default troffrc file when the formatter (usually
       groff(1)) is called with either of the options -Thtml or  -Txhtml.   To
       see  hyperlinks  in action, format this man page using one of those op‐
       tions.

       This document is a basic guide; the HTML output  driver  (grohtml)  re‐
       mains in an alpha state.  It has been included with the distribution to
       encourage testing.

       Here is a summary of the functions found in this macro set.

       .JOBNAME     split output into multiple files
       .HX          automatic heading level cut off
       .BCL         specify colours on a web page
       .BGIMG       specify background image
       .URL         create a URL using two parameters
       .FTP         create an FTP reference
       .MTO         create an HTML email address
       .TAG         generate an HTML name
       .IMG         include an image file
       .PIMG        include PNG image
       .MPIMG       place PNG on the margin and wrap text around it
       .HnS         begin heading
       .HnE         end heading
       .LK          emit automatically collected links.
       .HR          produce a horizontal rule
       .NHR         suppress automatic generation of rules.
       .HTL         only generate HTML title
       .HEAD        add data to <head> block
       .ULS         unorder list begin
       .ULE         unorder list end
       .OLS         ordered list begin
       .OLE         ordered list end
       .DLS         definition list begin
       .DLE         definition list end
       .LI          insert a list item
       .DC          generate a drop capital
       .HTML        pass an HTML raw request to the device driver
       .CDS         code example begin
       .CDE         code example end
       .ALN         place links on left of main text.
       .LNS         start a new two‐column table with links in the left.
       .LNE         end the two‐column table.
       .LINKSTYLE   initialize default URL attributes.

Macros
       .JOBNAME filename
              Split output into multiple HTML files.  A file is split whenever
              a  .SH  or  .NH 1 is encountered.  Its argument is the file stem
              name for future output files.   This  option  is  equivalent  to
              grohtml’s -j option.

       .HX n  Specify  the  cut  off  depth when generating links from section
              headings.  For example, a parameter of 2 would cause grohtml  to
              generate  a list of links for .NH 1 and .NH 2 but not for .NH 3.
              Whereas

                     .HX 0

              tells grohtml that no heading links should be  created  at  all.
              Another  method for turning automatic headings off is by issuing
              the command‐line switch -P-l to groff.

       .BCL foreground background active not‐visited visited
              This macro takes five parameters: foreground, background, active
              hypertext link, hypertext link not yet visited, and visited  hy‐
              pertext link colour.

       .BGIMG imagefile
              the only parameter to this macro is the background image file.

       .URL url [description] [after]
              generates  a URL using either one, two, or three arguments.  The
              first parameter is the actual URL, the second is the name of the
              link, and the third is optional stuff to be printed  immediately
              afterwards.   If  description  and after are absent then the URL
              becomes the anchor text.  Hyphenation is disabled while printing
              the actual URL; explicit breakpoints should be inserted with the
              \: escape sequence.  Here  is  how  to  encode  foo  ⟨http://foo
              .org/⟩:

                     .URL http://\:foo\:.org/ foo :

              If this is processed by a device other than -Thtml or -Txhtml it
              appears as:

                     foo ⟨http://foo.org⟩:

              The  URL macro can be of any type; for example, we can reference
              Eric Raymond’s pic guide ⟨pic.html⟩ by:

                     .URL pic\:.html "Eric Raymond's pic guide"

       .MTO address [description] [after]
              Generate an email HTML reference.  The first argument is  manda‐
              tory  as the email address.  The optional second argument is the
              text you see in your browser.  If an empty  argument  is  given,
              address  is  used  instead.  An optional third argument is stuff
              printed immediately afterwards.  Hyphenation is  disabled  while
              printing  the actual email address.  For example, Joe User ⟨joe@
              user.org⟩ can be achieved by the following macro:

                     .MTO joe@user.org "Joe User"

              All URLs currently are treated as consuming no textual space  in
              groff.   This  could be considered as a bug since it causes some
              problems.  To circumvent this,  www.tmac  inserts  a  zero‐width
              character  which  expands  to a harmless space (only if run with
              -Thtml or -Txhtml).

       .FTP url [description] [after]
              indicates that data can be obtained via FTP.  The first argument
              is the URL and the second is the browser text.   A  third  argu‐
              ment, similar to the macros above, is intended for stuff printed
              immediately  afterwards.  The second and the third parameter are
              optional.  Hyphenation is disabled  while  printing  the  actual
              URL.   As an example, here is the location of the GNU FTP server
              ⟨ftp://ftp.gnu.org/⟩.  The macro example above can be  specified
              as:

                     .FTP ftp://\:ftp\:.gnu\:.org/ "GNU FTP server" .

       .TAG name
              Generates  an HTML name tag from its argument.  This can then be
              referenced using the URL ⟨#URL⟩ macro.  As you can see, you must
              precede the tag name with # since it is a local reference.  This
              link was achieved via placing  a  TAG  in  the  URL  description
              above; the source looks like this:

                     .TP
                     .B URL
                     generates
                     .TAG URL
                     a URL using either two or three arguments.
                     ...

       .IMG [-R|-L|-C] filename [width] [height]
              Include  a picture into the document.  The first argument is the
              horizontal location: right, left, or center  (-R,  -L,  or  -C).
              Alignment  is  centered by default (-C).  The second argument is
              the filename.  The optional third and fourth arguments  are  the
              width and height.  If the width is absent it defaults to 1 inch.
              If  the  height  is  absent it defaults to the width.  This maps
              onto an HTML img tag.  If you are including a PNG image then  it
              is advisable to use the PIMG macro.

       .PIMG [-R|-L|-C] filename [width [height]]
              Include  an  image  in PNG format.  This macro takes exactly the
              same parameters as the IMG macro; it has the advantage of  work‐
              ing with PostScript and HTML devices also since it can automati‐
              cally convert the image into the EPS format, using the following
              programs  of the netpbm package: pngtopnm, pnmcrop, and pnmtops.
              If the document isn’t processed with -Thtml  or  -Txhtml  it  is
              necessary to use the -U option of groff.

       .MPIMG [-R|-L] [-G gap] filename [width [height]]
              Place  a  PNG  image on the margin and wrap text around it.  The
              first parameters are optional.  The alignment: left or right (-L
              or -R) specifies the margin where the picture is placed at.  The
              default alignment is left (-L).  Optionally, -G gap can be  used
              to  arrange  a  gap  between the picture and the text that wraps
              around it.  The default gap width is zero.
              The first non‐optional argument is the filename.   The  optional
              following  arguments  are the width and height.  If the width is
              absent it defaults to 1 inch.  If the height is  absent  it  de‐
              faults to the width.  Example:

                     .MPIMG -L -G 2c foo.png 3c 1.5c

              The  height  and  width  may  also be given as percentages.  The
              PostScript device calculates the width from the .l register  and
              the height from the .p register.  For example:

                     .MPIMG -L -G 2c foo.png 15%

       .HnS n Begin  heading.  The numeric heading level n is specified by the
              first parameter.  Use this macro if your headings  contain  URL,
              FTP or MTO macros.  Example:

                     .HnS 1
                     .HR
                     GNU Troff
                     .URL https://\:www\:.gnu\:.org/\:software/\:groff/
                     \[em]a
                     .URL http://www\:.gnu\:.org/ GNU
                     project.
                     .HR
                     .HnE

              In  this case you might wish to disable automatic links to head‐
              ings.  This can be done via -P-l from the command line.

       .HnE   End heading.

       .LK    Force grohtml to place the automatically generated links at this
              position.

       .HR    Generate a full‐width horizontal rule for  -Thtml  and  -Txhtml.
              No effect for all other devices.

       .NHR   Suppress  generation  of  the top and bottom rules which grohtml
              emits by default.

       .HTL   Generate an HTML title only.  This differs from the TL macro  of
              the  ms  macro package which generates both an HTML title and an
              <H1> heading.  Use it to provide an HTML title as search  engine
              fodder  but  a  graphic title in the document.  The macro termi‐
              nates when a space or break is seen (.sp, .br).

       .HEAD  Add arbitrary HTML data to the <head>  block.   Ignored  if  not
              processed with -Thtml or -Txhtml.  Example:

                     .HEAD "<link \
                       rel=""icon"" \
                       type=""image/png"" \
                       href=""http://foo.org//bar.png""/>"

       .HTML  All  text after this macro is treated as raw HTML.  If the docu‐
              ment is processed without -Thtml or -Txhtml then  the  macro  is
              ignored.  Internally, this macro is used as a building block for
              other higher‐level macros.

              For example, the BGIMG macro is defined as

                     .de BGIMG
                     .   HTML <body background=\\$1>
                     ..

       .DC l text [color]
              Produce a drop capital.  The first parameter is the letter to be
              dropped and enlarged, the second parameter text is the adjoining
              text  whose  height the first letter should not exceed.  The op‐
              tional third parameter is the color of the dropped  letter.   It
              defaults to black.

       .CDS   Start displaying a code section in constant width font.

       .CDE   End code display

       .ALN [color] [percentage]
              Place  section  heading  links  automatically to the left of the
              main text.  The color argument is optional and if present  indi‐
              cates which HTML background color is to be used under the links.
              The  optional percentage indicates the amount of width to devote
              to displaying the links.  The default values are #eeeeee and  30
              for color and percentage width, respectively.  This macro should
              only  be  called  once  at the beginning of the document.  After
              calling this macro each section heading emits an HTML table con‐
              sisting of the links in the left and the  section  text  on  the
              right.

       .LNS   Start  a  new  two‐column  table  with links in the left column.
              This can be called if the document has text before the first .SH
              and if .ALN is used.  Typically this is called just  before  the
              first  paragraph  and  after the main title as it indicates that
              text after this point should be positioned to the right  of  the
              left‐hand navigational links.

       .LNE   End a two‐column table.  This should be called at the end of the
              document if .ALN was used.

       .LINKSTYLE color [ fontstyle [ openglyph closeglyph ] ]
              Initialize  default  URL attributes to be used if this macro set
              is not used with the HTML device.  The macro set initializes it‐
              self with the following call

                     .LINKSTYLE blue CR \[la] \[ra]

              but these values will be superseded by a user call to LINKSTYLE.

Section heading links
       By default grohtml generates links to all section headings  and  places
       these at the top of the HTML document.  (See LINKS ⟨#LK⟩ for details of
       how to switch this off or alter the position).

Limitations of grohtml
       tbl(1)  tables are rendered as PNG images.  Paul DuBois’s approach with
       tblcvt(1), part of  the  troffcvt  distribution  ⟨http://www.snake.net/
       software/troffcvt/⟩, should be explored.

Files
       /usr/share/groff/1.23.0/tmac/www.tmac

Authors
       The  www  macro package was written by Gaius Mulley ⟨gaius@glam.ac.uk⟩,
       with  additions  by  Werner  Lemberg  ⟨wl@gnu.org⟩  and  Bernd   Warken
       ⟨groff-bernd.warken-72@web.de⟩.

See also
       groff(1), troff(1), grohtml(1), netpbm(1)

groff 1.23.0                      2 July 2023                     groff_www(7)
───────────────────────────────────────────────────────────────────────────────
roff(7)                Miscellaneous Information Manual                roff(7)

Name
       roff - concepts and history of roff typesetting

Description
       The  term roff denotes a family of document formatting systems known by
       names like troff, nroff, and ditroff.  A roff system consists of an in‐
       terpreter for an extensible text formatting language and a set of  pro‐
       grams for preparing output for various devices and file formats.  Unix‐
       like  operating  systems  often  distribute  a roff system.  The manual
       pages on Unix systems (“man pages”) and bestselling books  on  software
       engineering,  including Brian Kernighan and Dennis Ritchie’s The C Pro‐
       gramming Language and W. Richard Stevens’s Advanced Programming in  the
       Unix Environment have been written using roff systems.  GNU roff—groff—
       is arguably the most widespread roff implementation.

       Below we present typographical concepts that form the background of all
       roff implementations, narrate the development history of some roff sys‐
       tems,  detail the command pipeline managed by groff(1), survey the for‐
       matting language, suggest tips for editing roff  input,  and  recommend
       further reading materials.

Concepts
       roff input files contain text interspersed with instructions to control
       the  formatter.   Even in the absence of such instructions, a roff for‐
       matter still processes its input in several ways, by filling, hyphenat‐
       ing, breaking, and adjusting it, and supplementing it  with  inter‐sen‐
       tence space.  These processes are basic to typesetting, and can be con‐
       trolled at the input document’s discretion.

       When a device‐independent roff formatter starts up, it obtains informa‐
       tion  about  the  device for which it is preparing output from the lat‐
       ter’s description file (see groff_font(5)).  An essential  property  is
       the length of the output line, such as “6.5 inches”.

       The  formatter interprets plain text files employing the Unix line‐end‐
       ing convention.  It reads input a character at a time, collecting words
       as it goes, and fits as many words together on an  output  line  as  it
       can—this is known as filling.  To a roff system, a word is any sequence
       of  one  or more characters that aren’t spaces or newlines.  The excep‐
       tions separate words.

       A roff formatter attempts to detect boundaries between  sentences,  and
       supplies  additional  inter‐sentence space between them.  It flags cer‐
       tain characters (normally “!”, “?”, and “.”) as  potentially  ending  a
       sentence.   When  the formatter encounters one of these end‐of‐sentence
       characters at the end of an input line, or one of them is  followed  by
       two (unescaped) spaces on the same input line, it appends an inter‐word
       space  followed  by  an  inter‐sentence space in the output.  The dummy
       character escape sequence \& can be used after an end‐of‐sentence char‐
       acter to defeat end‐of‐sentence  detection  on  a  per‐instance  basis.
       Normally, the occurrence of a visible non‐end‐of‐sentence character (as
       opposed to a space or tab) immediately after an end‐of‐sentence charac‐
       ter cancels detection of the end of a sentence.  However, several char‐
       acters are treated transparently after the occurrence of an end‐of‐sen‐
       tence  character.   That is, a roff does not cancel end‐of‐sentence de‐
       tection when it processes them.  This is because  such  characters  are
       often  used  as footnote markers or to close quotations and parentheti‐
       cals.  The default set is ", ', ),  ],  *,  \[dg],  \[dd],  \[rq],  and
       \[cq].   The  last  four are examples of special characters, escape se‐
       quences whose purpose is to obtain glyphs that are not easily typed  at
       the keyboard, or which have special meaning to the formatter (like \).

       When  an  output  line is nearly full, it is uncommon for the next word
       collected from the input to exactly fill it—typically,  there  is  room
       left  over  only for part of the next word.  The process of splitting a
       word so that it appears partially on one line (with a hyphen  to  indi‐
       cate to the reader that the word has been broken) with its remainder on
       the next is hyphenation.  Hyphenation points can be manually specified;
       groff  also  uses a hyphenation algorithm and language‐specific pattern
       files to decide which words can be hyphenated and  where.   Hyphenation
       does  not always occur even when the hyphenation rules for a word allow
       it; it can be disabled, and when not disabled there are several parame‐
       ters that can prevent it in certain circumstances.

       Once an output line is full, the next word (or remainder of  a  hyphen‐
       ated one) is placed on a different output line; this is called a break.
       In  this  document  and in roff discussions generally, a “break” if not
       further qualified always refers to the termination of an  output  line.
       When  the formatter is filling text, it introduces breaks automatically
       to keep output lines from exceeding the configured line length.   After
       an  automatic  break,  a  roff formatter adjusts the line if applicable
       (see below), and then resumes collecting and filling text on  the  next
       output line.

       Sometimes,  a  line  cannot be broken automatically.  This usually does
       not happen with natural language text unless the output line length has
       been manipulated to be extremely short, but  it  can  with  specialized
       text  like  program source code.  groff provides a means of telling the
       formatter where the line may be broken without hyphens.  This  is  done
       with the non‐printing break point escape sequence \:.

       There  are  several ways to cause a break at a predictable location.  A
       blank input line not only causes a break, but by default it  also  out‐
       puts  a  one‐line  vertical  space  (effectively  a blank output line).
       Macro packages may discourage or disable this “blank  line  method”  of
       paragraphing in favor of their own macros.  A line that begins with one
       or  more spaces causes a break.  The spaces are output at the beginning
       of the next line without being  adjusted  (see  below).   Again,  macro
       packages  may  provide  other methods of producing indented paragraphs.
       Trailing spaces on text lines (see below) are discarded.   The  end  of
       input causes a break.

       After the formatter performs an automatic break, it may then adjust the
       line,  widening inter‐word spaces until the text reaches the right mar‐
       gin.  Extra spaces between words are preserved.  Leading  and  trailing
       spaces  are handled as noted above.  Text can be aligned to the left or
       right margin only, or centered, using requests.

       A roff formatter translates horizontal tab characters, also called sim‐
       ply “tabs”, in the input into movements to the next  tab  stop.   These
       tab stops are by default located every half inch measured from the cur‐
       rent position on the input line.  With them, simple tables can be made.
       However, this method can be deceptive, as the appearance (and width) of
       the  text  in  an  editor  and  the results from the formatter can vary
       greatly, particularly when proportional  typefaces  are  used.   A  tab
       character does not cause a break and therefore does not interrupt fill‐
       ing.   The formatter provides facilities for sophisticated table compo‐
       sition; there are many details  to  track  when  using  the  “tab”  and
       “field” low‐level features, so most users turn to the tbl(1) preproces‐
       sor to lay out tables.

   Requests and macros
       A  request  is an instruction to the formatter that occurs after a con‐
       trol character, which is recognized at the beginning of an input  line.
       The  regular  control character is a dot “.”.  Its counterpart, the no‐
       break control character, a neutral apostrophe “'”, suppresses the break
       implied by some requests.  These characters were chosen because  it  is
       uncommon for lines of text in natural languages to begin with them.  If
       you  require a formatted period or apostrophe (closing single quotation
       mark) where the formatter is expecting a control character, prefix  the
       dot  or  neutral  apostrophe  with the dummy character escape sequence,
       “\&”.

       An input line beginning with a control character is  called  a  control
       line.  Every line of input that is not a control line is a text line.

       Requests  often  take arguments, words (separated from the request name
       and each other by spaces) that specify details of the action  the  for‐
       matter is expected to perform.  If a request is meaningless without ar‐
       guments,  it  is typically ignored.  Of key importance are the requests
       that define macros.  Macros are invoked like requests, enabling the re‐
       quest repertoire to be extended or overridden.

       A macro can be thought of as an abbreviation you can define for a  col‐
       lection  of control and text lines.  When the macro is called by giving
       its name after a control character, it is replaced with what it  stands
       for.   The  process  of  textual replacement is known as interpolation.
       Interpolations are handled as soon as they  are  recognized,  and  once
       performed, a roff formatter scans the replacement for further requests,
       macro calls, and escape sequences.

       In roff systems, the “de” request defines a macro.

   Page geometry
       roff  systems  format  text under certain assumptions about the size of
       the output medium, or page.  For the formatter  to  correctly  break  a
       line it is filling, it must know the line length, which it derives from
       the  page  width.   For it to decide whether to write an output line to
       the current page or wait until the next one,  it  must  know  the  page
       length.   A device’s resolution converts practical units like inches or
       centimeters to basic units, a convenient length measure for the  output
       device or file format.  The formatter and output driver use basic units
       to  reckon  page measurements.  The device description file defines its
       resolution and page dimensions (see groff_font(5)).

       A page is a two‐dimensional structure upon which a roff system  imposes
       a  rectangular coordinate system with its upper left corner as the ori‐
       gin.  Coordinate values are in basic units and increase down and to the
       right.  Useful ones are therefore always positive  and  within  numeric
       ranges corresponding to the page boundaries.

       While  the  formatter (and, later, output driver) is processing a page,
       it keeps track of its drawing position, which is the location at  which
       the next glyph will be written, from which the next motion will be mea‐
       sured,  or  where  a geometric object will commence rendering.  Notion‐
       ally, glyphs are drawn from the text baseline upward and to the  right.
       (groff  does not yet support right‐to‐left scripts.)  The text baseline
       is a (usually invisible) line upon which the glyphs of a  typeface  are
       aligned.   A  glyph  therefore  “starts” at its bottom‐left corner.  If
       drawn at the origin, a typical letter  glyph  would  lie  partially  or
       wholly  off the page, depending on whether, like “g”, it features a de‐
       scender below the baseline.

       Such a situation is nearly always undesirable.  It is furthermore  con‐
       ventional  not  to  write  or  draw  at  the extreme edges of the page.
       Therefore the initial drawing position of a roff formatter  is  not  at
       the  origin,  but  below  and to the right of it.  This rightward shift
       from the left edge is known as the page offset.  (groff’s terminal out‐
       put devices have page offsets of zero.)  The downward shift leaves room
       for a text output line.

       Text is arranged on a one‐dimensional lattice of  text  baselines  from
       the  top  to  the bottom of the page.  Vertical spacing is the distance
       between adjacent text baselines.  Typographic tradition sets this quan‐
       tity to 120% of the type size.  The initial vertical  drawing  position
       is  one unit of vertical spacing below the page top.  Typographers term
       this unit a vee.

       Vertical spacing has an impact on page‐breaking decisions.   Generally,
       when  a  break  occurs, the formatter moves the drawing position to the
       next text baseline automatically.  If the formatter were already  writ‐
       ing  to  the last line that would fit on the page, advancing by one vee
       would place the next text baseline off the page.  Rather than let  that
       happen,  roff  formatters instruct the output driver to eject the page,
       start a new one, and again set the drawing position to  one  vee  below
       the page top; this is a page break.

       When  the  last  line of input text corresponds to the last output line
       that fits on the page, the break caused by the end of input  will  also
       break  the  page,  producing  a useless blank one.  Macro packages keep
       users from having to confront this difficulty by setting “traps”; more‐
       over, all but the simplest page layouts tend to have headers and  foot‐
       ers, or at least bear vertical margins larger than one vee.

   Other language elements
       Escape  sequences  start  with the escape character, a backslash \, and
       are followed by at least one additional  character.   They  can  appear
       anywhere in the input.

       With  requests,  the escape and control characters can be changed; fur‐
       ther, escape sequence recognition can be turned off and back on.

       Strings store character sequences.  In groff, they can be parameterized
       as macros can.

       Registers store numerical values, including measurements.   The  latter
       are  generally in basic units; scaling units can be appended to numeric
       expressions to clarify their meaning when stored or interpolated.  Some
       read‐only predefined registers interpolate text.

       Fonts are identified either by a name or by a mounting position (a non‐
       negative number).  Four styles are available on all devices.  R is “ro‐
       man”: normal, upright text.  B is bold,  an  upright  typeface  with  a
       heavier weight.  I is italic, a face that is oblique on typesetter out‐
       put  devices and usually underlined instead on terminal devices.  BI is
       bold‐italic, combining both of the foregoing style  variations.   Type‐
       setting  devices  group  these four styles into families of text fonts;
       they also typically offer one or more special fonts  that  provide  un‐
       styled glyphs; see groff_char(7).

       groff  supports named colors for glyph rendering and drawing of geomet‐
       ric objects.  Stroke and fill colors are distinct; the stroke color  is
       used for glyphs.

       Glyphs  are  visual  representation forms of characters.  In groff, the
       distinction between those two elements is not  always  obvious  (and  a
       full  discussion  is  beyond  our scope).  In brief, “A” is a character
       when we consider it in the abstract: to make it a glyph, we must select
       a typeface with which to render it, and determine  its  type  size  and
       color.   The  formatting  process  turns  input  characters into output
       glyphs.  A few characters commonly seen on keyboards are  treated  spe‐
       cially  by the roff language and may not look correct in output if used
       unthinkingly; they are the (double) quotation  mark  ("),  the  neutral
       apostrophe  ('),  the  minus  sign (-), the backslash (\), the caret or
       circumflex accent (^), the grave accent (`), and the tilde (~).  All of
       these and more can be produced with special character escape sequences;
       see groff_char(7).

       groff offers streams, identifiers for writable files, but for  security
       reasons this feature is disabled by default.

       A  further  few language elements arise as page layouts become more so‐
       phisticated and demanding.  Environments collect formatting  parameters
       like line length and typeface.  A diversion stores formatted output for
       later  use.  A trap is a condition on the input or output, tested auto‐
       matically by the formatter, that is associated with a macro, calling it
       when that condition is fulfilled.

       Footnote support often exercises all three of the  foregoing  features.
       A simple implementation might work as follows.  A pair of macros is de‐
       fined:  one  starts a footnote and the other ends it.  The author calls
       the first macro where a footnote marker is desired.  The  macro  estab‐
       lishes  a diversion so that the footnote text is collected at the place
       in the body text where its corresponding marker appears.   An  environ‐
       ment  is  created for the footnote so that it is set at a smaller type‐
       face.  The footnote text is formatted in the diversion using that envi‐
       ronment, but it does not yet appear in the output.  The document author
       calls the footnote end macro, which returns to the previous environment
       and ends the diversion.  Later, after much more body text in the  docu‐
       ment,  a  trap,  set a small distance above the page bottom, is sprung.
       The macro called by the trap draws a line across the page and emits the
       stored diversion.  Thus, the footnote is rendered.

History
       Computer‐driven document formatting dates back to the 1960s.  The  roff
       system  is intimately connected with Unix, but its origins lie with the
       earlier operating systems CTSS, GECOS, and Multics.

   The predecessor—RUNOFF
       roff’s ancestor RUNOFF was written in the MAD language by Jerry Saltzer
       to prepare his Ph.D. thesis  on  the  Compatible  Time  Sharing  System
       (CTSS),  a  project of the Massachusetts Institute of Technology (MIT).
       This program is referred to in full capitals, both  to  distinguish  it
       from  its  many  descendants,  and because bits were expensive in those
       days; five‐ and six‐bit character encodings were  still  in  widespread
       usage,  and  mixed‐case  alphabetics  in  file  names seen as a luxury.
       RUNOFF introduced a syntax of inlining formatting directives amid docu‐
       ment text, by beginning a line with a period (an unlikely occurrence in
       human‐readable material) followed by a “control word”.   Control  words
       with obvious meaning like “.line length n” were supported as well as an
       abbreviation system; the latter came to overwhelm the former in popular
       usage  and later derivatives of the program.  A sample of control words
       from a RUNOFF manual of December 1966  ⟨http://web.mit.edu/Saltzer/www/
       publications/ctss/AH.9.01.html⟩ was documented as follows (with the pa‐
       rameter notation slightly altered).  The abbreviations will be familiar
       to roff veterans.

                           Abbreviation   Control word
                                    .ad   .adjust
                                    .bp   .begin page
                                    .br   .break
                                    .ce   .center
                                    .in   .indent n
                                    .ll   .line length n
                                    .nf   .nofill
                                    .pl   .paper length n
                                    .sp   .space [n]

       In  1965, MIT’s Project MAC teamed with Bell Telephone Laboratories and
       General Electric (GE) to inaugurate the Multics  ⟨http://www.multicians
       .org⟩  project.  After a few years, Bell Labs discontinued its partici‐
       pation in Multics, famously prompting the development of  Unix.   Mean‐
       while,  Saltzer’s  RUNOFF proved influential, seeing many ports and de‐
       rivations elsewhere.

       In 1969, Doug McIlroy wrote one such  reimplementation,  adding  exten‐
       sions, in the BCPL language for a GE 645 running GECOS at the Bell Labs
       location  in  Murray Hill, New Jersey.  In its manual, the control com‐
       mands were termed “requests”, their two‐letter  names  were  canonical,
       and  the  control character was configurable with a .cc request.  Other
       familiar requests emerged at this time; no‐adjust  (.na),  need  (.ne),
       page  offset  (.po),  tab  configuration (.ta, though it worked differ‐
       ently), temporary indent (.ti), character translation (.tr), and  auto‐
       matic  underlining  (.ul; on RUNOFF you had to backspace and underscore
       in the input yourself).  .fi to enable filling of output lines got  the
       name it retains to this day.  McIlroy’s program also featured a heuris‐
       tic  system  for automatically placing hyphenation points, designed and
       implemented by Molly Wagner.  It furthermore introduced  numeric  vari‐
       ables, termed registers.  By 1971, this program had been ported to Mul‐
       tics and was known as roff, a name McIlroy attributes to Bob Morris, to
       distinguish it from CTSS RUNOFF.

   Unix and roff
       McIlroy’s  roff was one of the first Unix programs.  In Ritchie’s term,
       it was “transliterated” from BCPL to DEC PDP‐7  assembly  language  for
       the fledgling Unix operating system.  Automatic hyphenation was managed
       with  .hc  and  .hy requests, line spacing control was generalized with
       the .ls request, and what later roffs would call diversions were avail‐
       able via “footnote” requests.  This roff  indirectly  funded  operating
       systems  research  at Murray Hill; AT&T prepared patent applications to
       the U.S. government with it.  This arrangement enabled the group to ac‐
       quire a PDP‐11; roff promptly proved equal to the  task  of  formatting
       the  manual  for what would become known as “First Edition Unix”, dated
       November 1971.

       Output from all of the foregoing programs was limited to line  printers
       and  paper  terminals such as the IBM 2471 (based on the Selectric line
       of typewriters) and the Teletype Corporation Model 37.   Proportionally
       spaced type was unavailable.

   New roff and Typesetter roff
       The first years of Unix were spent in rapid evolution.  The practicali‐
       ties  of preparing standardized documents like patent applications (and
       Unix manual pages), combined with McIlroy’s enthusiasm for  macro  lan‐
       guages,  perhaps created an irresistible pressure to make roff extensi‐
       ble.  Joe Ossanna’s nroff, literally a “new roff”, was the  outlet  for
       this pressure.  By the time of Unix Version 3 (February 1973)—and still
       in  PDP‐11 assembly language—it sported a swath of features now consid‐
       ered essential to roff systems: definition of macros  (.de),  diversion
       of  text  thither (.di), and removal thereof (.rm); trap planting (.wh;
       “when”) and relocation (.ch; “change”); conditional  processing  (.if);
       and  environments  (.ev).  Incremental improvements included assignment
       of the next page number (.pn); no‐space mode (.ns) and  restoration  of
       vertical  spacing  (.rs); the saving (.sv) and output (.os) of vertical
       space; specification of replacement characters for tabs (.tc) and lead‐
       ers (.lc); configuration  of  the  no‐break  control  character  (.c2);
       shorthand  to  disable  automatic  hyphenation (.nh); a condensation of
       what were formerly six different requests  for  configuration  of  page
       “titles”  (headers and footers) into one (.tl) with a length controlled
       separately from the line length (.lt); automatic line numbering  (.nm);
       interactive  input (.rd), which necessitated buffer‐flushing (.fl), and
       was made convenient with early program cessation (.ex); source file in‐
       clusion in its modern form (.so; though RUNOFF had an “.append” control
       word for a similar purpose) and early advance to the next file argument
       (.nx); ignorable content (.ig); and programmable abort (.ab).

       Third Edition Unix also brought the pipe(2) system call, the  explosive
       growth  of a componentized system based around it, and a “filter model”
       that remains perceptible today.  Equally  importantly,  the  Bell  Labs
       site  in  Murray Hill acquired a Graphic Systems C/A/T phototypesetter,
       and with it came the necessity of expanding the capabilities of a  roff
       system  to  cope  with  a variety of proportionally spaced typefaces at
       multiple sizes.  Ossanna wrote a parallel implementation of  nroff  for
       the  C/A/T,  dubbing  it troff (for “typesetter roff”).  Unfortunately,
       surviving documentation does not illustrate what requests  were  imple‐
       mented  at this time for C/A/T support; the troff(1) man page in Fourth
       Edition Unix (November 1973) does not feature a  request  list,  unlike
       nroff(1).   Apart from typesetter‐driven features, Unix Version 4 roffs
       added string definitions (.ds); made the escape character  configurable
       (.ec);  and enabled the user to write diagnostics to the standard error
       stream (.tm).  Around 1974, empowered with multiple type  sizes,  ital‐
       ics, and a symbol font specially commissioned by Bell Labs from Graphic
       Systems,  Kernighan  and Lorinda Cherry implemented eqn for typesetting
       mathematics.  In the same year, for Fifth Edition  Unix,  Ossanna  com‐
       bined  and reimplemented the two roffs in C, using that language’s pre‐
       processor to generate both from a single source tree.

       Ossanna documented the syntax of the input language to  the  nroff  and
       troff  programs  in the “Troff User’s Manual”, first published in 1976,
       with further revisions as late as 1992  by  Kernighan.   (The  original
       version  was  entitled “Nroff/Troff User’s Manual”, which may partially
       explain why roff practitioners have tended to refer to it by  its  AT&T
       document  identifier, “CSTR #54”.)  Its final revision serves as the de
       facto specification of AT&T troff, and all subsequent  implementors  of
       roff systems have done so in its shadow.

       A  small  and  simple  set of roff macros was first used for the manual
       pages of Unix Version 4 and persisted for two further releases, but the
       first macro package to be formally described and installed  was  ms  by
       Michael  Lesk  in Version 6.  He also wrote a manual, “Typing Documents
       on the Unix System”, describing ms and basic nroff/troff usage,  updat‐
       ing it as the package accrued features.  Sixth Edition additionally saw
       the debut of the tbl preprocessor for formatting tables, also by Lesk.

       For  Unix  Version 7 (January 1979), McIlroy designed, implemented, and
       documented the man macro package, introducing most of  the  macros  de‐
       scribed  in  groff_man(7)  today,  and edited volume 1 of the Version 7
       manual using it.  Documents composed using ms  featured  in  volume  2,
       edited by Kernighan.

       Meanwhile,  troff proved popular even at Unix sites that lacked a C/A/T
       device.  Tom Ferrin of the University of California  at  San  Francisco
       combined  it  with  Allen  Hershey’s  popular  vector  fonts to produce
       vtroff, which translated troff’s output to the command language used by
       Versatec and Benson‐Varian plotters.

       Ossanna had passed away unexpectedly in 1977, and after the release  of
       Version 7, with the C/A/T typesetter becoming supplanted by alternative
       devices  such  as  the Mergenthaler Linotron 202, Kernighan undertook a
       revision and rewrite of troff to generalize its design.   To  implement
       this revised architecture, he developed the font and device description
       file  formats  and the page description language that remain in use to‐
       day.  He described these novelties in the article  “A  Typesetter‐inde‐
       pendent TROFF”, last revised in 1982, and like the troff manual itself,
       it is widely known by a shorthand, “CSTR #97”.

       Kernighan’s innovations prepared troff well for the introduction of the
       Adobe  PostScript language in 1982 and a vibrant market in laser print‐
       ers with built‐in interpreters for it.   An  output  driver  for  Post‐
       Script, dpost, was swiftly developed.  However, AT&T’s software licens‐
       ing  practices  kept  Ossanna’s  troff,  with its tight coupling to the
       C/A/T’s capabilities, in parallel distribution with  device‐independent
       troff  throughout  the  1980s.  Today, however, all actively maintained
       troffs follow Kernighan’s device‐independent design.

   groff—a free roff from GNU
       The most important free roff project historically has been  groff,  the
       GNU  implementation of troff, developed by James Clark starting in 1989
       and distributed under copyleft ⟨http://www.gnu.org/copyleft⟩  licenses,
       ensuring to all the availability of source code and the freedom to mod‐
       ify  and  redistribute  it, properties unprecedented in roff systems to
       that point.  groff rapidly attracted contributors, and has served as  a
       replacement  for  almost all applications of AT&T troff (exceptions in‐
       clude mv, a macro package for preparation of viewgraphs and slides, and
       the ideal preprocessor, which produces diagrams from mathematical  con‐
       straints).    Beyond   that,   it  has  added  numerous  features;  see
       groff_diff(7).  Since its inception and  for  at  least  the  following
       three  decades,  it  has been used by practically all GNU/Linux and BSD
       operating systems.

       groff continues to be developed, is available for almost all  operating
       systems  in  common use (along with several obscure ones), and is free.
       These factors make groff the de facto roff standard today.

   Other free roffs
       In 2007, Caldera/SCO and Sun Microsystems, having  acquired  rights  to
       AT&T  Documenter’s Workbench (DWB) troff (a descendant of the Bell Labs
       code), released it under a free but GPL‐incompatible license.  This im‐
       plementation ⟨https://github.com/n-t-roff/DWB3.3⟩ was made portable  to
       modern  POSIX  systems, and adopted and enhanced first by Gunnar Ritter
       and  then  Carsten   Kunze   to   produce   Heirloom   Doctools   troff
       ⟨https://github.com/n‐t‐roff/heirloom‐doctools⟩.

       In  July 2013, Ali Gholami Rudi announced neatroff ⟨https://github.com/
       aligrudi/neatroff⟩, a permissively licensed new implementation.

       Another descendant of DWB troff is part  of  Plan  9  from  User  Space
       ⟨https://9fans.github.io/plan9port/⟩.   Since 2021, this troff has been
       available under permissive terms.

Using roff
       When you read a man page, often a roff is  the  program  rendering  it.
       Some roff implementations provide wrapper programs that make it easy to
       use  the  roff system from the shell’s command line.  These can be spe‐
       cific to a macro package, like mmroff(1), or  more  general.   groff(1)
       provides  command‐line  options  sparing the user from constructing the
       long, order‐dependent pipelines familiar to AT&T troff users.  Further,
       a heuristic program, grog(1), is available to infer from  a  document’s
       contents which groff arguments should be used to process it.

   The roff pipeline
       A  typical  roff document is prepared by running one or more processors
       in series, followed by a a formatter program and then an output  driver
       (or  “device  postprocessor”).  Commonly, these programs are structured
       into a pipeline; that is, each is run in sequence such that the  output
       of  one is taken as the input to the next, without passing through sec‐
       ondary storage.  (On non‐Unix systems, pipelines may have to  be  simu‐
       lated with temporary files.)

              $ preproc1 < input‐file | preproc2 | ... | troff [option] ... \
                  | output‐driver

       Once  all preprocessors have run, they deliver pure roff language input
       to the formatter, which in turn generates a document in a page descrip‐
       tion language that is then interpreted by a postprocessor for  viewing,
       printing, or further processing.

       Each  program interprets input in a language that is independent of the
       others; some are purely descriptive, as with tbl(1)  and  roff  output,
       and  some  permit the definition of macros, as with eqn(1) and roff in‐
       put.  Most roff input files employ the macros of a document  formatting
       package,  intermixed  with  instructions for one or more preprocessors,
       and seasoned with escape sequences and requests from the roff language.
       Some documents are simpler still, since their formatting packages  dis‐
       courage direct use of roff requests; man pages are a prominent example.
       Many features of the roff language are seldom needed by users; only au‐
       thors of macro packages require a substantial command of them.

   Preprocessors
       A  roff  preprocessor is a program that, directly or ultimately, gener‐
       ates output in the roff language.  Typically, each preprocessor defines
       a language of its own that transforms its input into that for  roff  or
       another  preprocessor.   As an example of the latter, chem produces pic
       input.  Preprocessors must consequently be run in an appropriate order;
       groff(1) handles this automatically for all preprocessors  supplied  by
       the GNU roff system.

       Portions  of the document written in preprocessor languages are usually
       bracketed by tokens that look like roff macro calls.  roff preprocessor
       programs transform only the regions of the document intended for  them.
       When  a  preprocessor language is used by a document, its corresponding
       program must process it before the input is seen by the  formatter,  or
       incorrect rendering is almost guaranteed.

       GNU  roff provides several preprocessors, including eqn, grn, pic, tbl,
       refer, and soelim.  See groff(1) for a complete list.  Other preproces‐
       sors for roff systems are known.

              dformat   depicts data structures;
              grap      constructs statistical charts; and
              ideal     draws diagrams using a constraint‐based language.

   Formatter programs
       A roff formatter transforms roff language input into a single file in a
       page description language, described in groff_out(5), intended for pro‐
       cessing by a selected device.  This page description language  is  spe‐
       cialized  in  its  parameters, but not its syntax, for the selected de‐
       vice; the format is device‐independent, but not  device‐agnostic.   The
       parameters the formatter uses to arrange the document are stored in de‐
       vice and font description files; see groff_font(5).

       AT&T  Unix  had two formatters—nroff for terminals, and troff for type‐
       setters.  Often, the name troff is used loosely to refer to both.  When
       generalizing thus, groff documentation prefers the term “roff”.  In GNU
       roff, the formatter program is always troff(1).

   Devices and output drivers
       To a roff system, a device is a hardware interface like  a  printer,  a
       text  or  graphical  terminal, or a standardized file format that unre‐
       lated software can interpret.  An  output  driver  is  a  program  that
       parses  the  output  of troff and produces instructions specific to the
       device or file format it supports.  An output driver might support mul‐
       tiple devices, particularly if they are similar.

       The names of the devices and their driver programs  are  not  standard‐
       ized.   Technological  fashions  evolve;  the devices used for document
       preparation when AT&T troff was first  written  in  the  1970s  are  no
       longer  used  in  production  environments.   Device  capabilities have
       tended to increase,  improving  resolution  and  font  repertoire,  and
       adding color output and hyperlinking.  Further, to reduce file size and
       processing time, AT&T troff’s page description language placed low lim‐
       its on the magnitudes of some quantities it could represent.  Its Post‐
       Script output driver, dpost(1), had a resolution of 720 units per inch;
       groff’s grops(1) uses 72,000.

roff programming
       Documents  using  roff are normal text files interleaved with roff for‐
       matting elements.  The roff language is powerful enough to support  ar‐
       bitrary  computation  and  it supplies facilities that encourage exten‐
       sion.  The primary such facility is macro definition;  with  this  fea‐
       ture, macro packages have been developed that are tailored for particu‐
       lar applications.

   Macro packages
       Macro  packages  can  have  a much smaller vocabulary than roff itself;
       this trait combined with their domain‐specific  nature  can  make  them
       easy  to  acquire  and  master.  The macro definitions of a package are
       typically kept in a file called  name.tmac  (historically,  tmac.name).
       Find  details  on  the  naming  and  placement  of  macro  packages  in
       groff_tmac(5).

       A macro package anticipated for use in a document can  be  declared  to
       the  formatter by the command‐line option -m; see troff(1).  It can al‐
       ternatively be specified within a document using the mso request of the
       groff language; see groff(7).

       Well‐known macro packages include man for  traditional  man  pages  and
       mdoc for BSD‐style manual pages.  Macro packages for typesetting books,
       articles,  and letters include ms (from “manuscript macros”), me (named
       by a system administrator from the first name of its creator, Eric All‐
       man), mm (from “memorandum macros”), and mom, a punningly named package
       exercising many groff extensions.  See groff_tmac(5) for more.

   The roff formatting language
       The roff language provides requests, escape sequences, macro definition
       facilities, string variables, registers for storage of numbers  or  di‐
       mensions, and control of execution flow.  The theoretically minded will
       observe that a roff is not a mere markup language, but Turing‐complete.
       It has storage (registers), it can perform tests (as in conditional ex‐
       pressions like “(\n[i] >= 1)”), its “if” and related requests alter the
       flow of control, and macro definition permits unbounded recursion.

       Requests and escape sequences are instructions, predefined parts of the
       language, that perform formatting operations, interpolate stored mater‐
       ial,  or otherwise change the state of the parser.  The user can define
       their own request‐like elements by composing together  text,  requests,
       and  escape sequences ad libitum.  A document writer will not (usually)
       note any difference in usage for requests or macros; both are found  on
       control lines.  However, there is a distinction; requests take either a
       fixed  number  of arguments (sometimes zero), silently ignoring any ex‐
       cess, or consume the rest of the input line, whereas macros can take  a
       variable number of arguments.  Since arguments are separated by spaces,
       macros  require  a  means of embedding a space in an argument; in other
       words, of quoting it.  This then demands a mechanism of  embedding  the
       quoting character itself, in case it is needed literally in a macro ar‐
       gument.  AT&T troff had complex rules involving the placement and repe‐
       tition  of the double quote to achieve both aims.  groff cuts this knot
       by supporting a special character escape sequence for the neutral  dou‐
       ble  quote,  “\[dq]”,  which  never performs quoting in the typesetting
       language, but is simply a glyph, ‘"’.

       Escape sequences start with a backslash, “\”.  They can  appear  almost
       anywhere,  even  in  the midst of text on a line, and implement various
       features, including the insertion of special characters with “\(xx”  or
       “\[xxx]”,  break  suppression  at  input  line  endings with “\c”, font
       changes with “\f”, type size changes with “\s”, in‐line  comments  with
       “\"”, and many others.

       Strings  store text.  They are populated with the ds request and inter‐
       polated using the \* escape sequence.

       Registers store numbers and measurements.  A register can be  set  with
       the  request  nr  and its value can be retrieved by the escape sequence
       \n.

File naming conventions
       The structure or content of a file name, beyond  its  location  in  the
       file  system, is not significant to roff tools.  roff documents employ‐
       ing “full‐service” macro packages (see groff_tmac(5)) tend to be  named
       with a suffix identifying the package; we thus see file names ending in
       .man, .ms, .me, .mm, and .mom, for instance.  When installed, man pages
       tend  to  be named with the manual’s section number as the suffix.  For
       example, the file name for this document is roff.7.  Practice for “raw”
       roff documents is less consistent; they are sometimes seen  with  a  .t
       suffix.

Input conventions
       Since troff fills text automatically, it is common practice in the roff
       language  to  avoid  visual composition of text in input files: the es‐
       thetic appeal of the formatted output is what matters.  Therefore, roff
       input should be arranged such that it is easy for authors and maintain‐
       ers to compose and develop the document, understand the syntax of  roff
       requests, macro calls, and preprocessor languages used, and predict the
       behavior  of the formatter.  Several traditions have accrued in service
       of these goals.

       • Follow sentence endings in the input  with  newlines  to  ease  their
         recognition.   It  is  frequently  convenient to end text lines after
         colons and semicolons as well, as these typically precede independent
         clauses.  Consider doing so after commas; they often occur  in  lists
         that become easy to scan when itemized by line, or constitute supple‐
         ments  to the sentence that are added, deleted, or updated to clarify
         it.  Parenthetical and quoted phrases are also  good  candidates  for
         placement on text lines by themselves.

       • Set your text editor’s line length to 72 characters or fewer; see the
         subsections  below.   This  limit, combined with the previous item of
         advice, makes it less common that an input line  will  wrap  in  your
         text  editor,  and  thus will help you perceive excessively long con‐
         structions in your text.  Recall that natural languages originate  in
         speech,  not  writing, and that punctuation is correlated with pauses
         for breathing and changes in prosody.

       • Use \& after “!”, “?”, and “.” if they are followed by space, tab, or
         newline characters and don’t end a sentence.

       • In filled text lines, use \& before “.” and “'” if they are  preceded
         by  space, so that reflowing the input doesn’t turn them into control
         lines.

       • Do not use spaces to perform indentation or align columns of a table.
         Leading spaces are reliable when text is not being filled.

       • Comment your document.  It is never too soon  to  apply  comments  to
         record  information  of use to future document maintainers (including
         your future self).  The \" escape sequence causes troff to ignore the
         remainder of the input line.

       • Use the empty request—a control character followed immediately  by  a
         newline—to  visually  manage  separation  of material in input files.
         Many of the groff project’s own documents use an  empty  request  be‐
         tween  sentences,  after  macro definitions, and where a break is ex‐
         pected, and two empty requests between paragraphs or  other  requests
         or  macro calls that will introduce vertical space into the document.
         You can combine the empty request with the comment escape sequence to
         include whole‐line comments in your document, and even “comment  out”
         sections of it.

       An  example  sufficiently  long to illustrate most of the above sugges‐
       tions in practice follows.  An arrow → indicates a tab character.

              .\"   nroff this_file.roff | less
              .\"   groff -T ps this_file.roff > this_file.ps
              →The theory of relativity is intimately connected with
              the theory of space and time.
              .
              I shall therefore begin with a brief investigation of
              the origin of our ideas of space and time,
              although in doing so I know that I introduce a
              controversial subject.  \" remainder of paragraph elided
              .
              .

              →The experiences of an individual appear to us arranged
              in a series of events;
              in this series the single events which we remember
              appear to be ordered according to the criterion of
              \[lq]earlier\[rq] and \[lq]later\[rq], \" punct swapped
              which cannot be analysed further.
              .
              There exists,
              therefore,
              for the individual,
              an I-time,
              or subjective time.
              .
              This itself is not measurable.
              .
              I can,
              indeed,
              associate numbers with the events,
              in such a way that the greater number is associated with
              the later event than with an earlier one;
              but the nature of this association may be quite
              arbitrary.
              .
              This association I can define by means of a clock by
              comparing the order of events furnished by the clock
              with the order of a given series of events.
              .
              We understand by a clock something which provides a
              series of events which can be counted,
              and which has other properties of which we shall speak
              later.
              .\" Albert Einstein, _The Meaning of Relativity_, 1922

   Editing with Emacs
       Official GNU doctrine holds that the best program for  editing  a  roff
       document  is Emacs; see emacs(1).  It provides an nroff major mode that
       is suitable for all kinds of roff dialects.  This mode can be activated
       by the following methods.

       When editing a file within Emacs the mode can be changed by typing “M‐x
       nroff-mode”, where M‐x means to hold down the meta key (often  labelled
       “Alt”) while pressing and releasing the “x” key.

       It is also possible to have the mode automatically selected when a roff
       file is loaded into the editor.

       • The most general method is to include file‐local variables at the end
         of the file; we can also configure the fill column this way.

                .\" Local Variables:
                .\" fill-column: 72
                .\" mode: nroff
                .\" End:

       • Certain  file  name  extensions,  such  as those commonly used by man
         pages, trigger the automatic activation of the nroff mode.

       • Technically, having the sequence

                .\" -*- nroff -*-

         in the first line of a file will cause Emacs to enter the nroff major
         mode when it is loaded into the buffer.  Unfortunately,  some  imple‐
         mentations of the man(1) program are confused by this practice, so we
         discourage it.

   Editing with Vim
       Other editors provide support for roff‐style files too, such as vim(1),
       an  extension  of the vi(1) program.  Vim’s highlighting can be made to
       recognize roff files by setting the filetype option in a Vim  modeline.
       For  this  feature to work, your copy of vim must be built with support
       for, and configured to enable, several features; consult  the  editor’s
       online  help topics “auto-setting”, “filetype”, and “syntax”.  Then put
       the following at the end of your roff files, after any Emacs configura‐
       tion:

                     .\" vim: set filetype=groff textwidth=72:

       Replace “groff” in the above with “nroff” if you want highlighting that
       does not recognize many of the GNU extensions to roff, such as request,
       register, and string names longer than two characters.

Authors
       This document was written by  Bernd  Warken  ⟨groff-bernd.warken-72@web
       .de⟩ and G. Branden Robinson ⟨g.branden.robinson@gmail.com⟩.

See also
       Much  roff documentation is available.  The Bell Labs papers describing
       AT&T troff remain available, and groff is documented comprehensively.

   Internet sites
       Unix       Text       Processing       ⟨https://github.com/larrykollar/
       Unix-Text-Processing⟩, by Dale Dougherty and Tim O’Reilly, 1987, Hayden
       Books.   This  well‐regarded  text brings the reader from a state of no
       knowledge of Unix or text editing (if necessary) to sophisticated  com‐
       puter‐aided  typesetting.  It has been placed under a free software li‐
       cense by its authors and updated by a team of  groff  contributors  and
       enthusiasts.

       “History  of  Unix  Manpages” ⟨http://manpages.bsd.lv/history.html⟩, an
       online article maintained by the mdocml project, provides  an  overview
       of roff development from Saltzer’s RUNOFF to 2008, with links to origi‐
       nal  documentation and recollections of the authors and their contempo‐
       raries.

       troff.org ⟨http://www.troff.org/⟩, Ralph Corderoy’s  troff  site,  pro‐
       vides an overview and pointers to much historical roff information.

       Multicians ⟨http://www.multicians.org/⟩, a site by Multics enthusiasts,
       contains a lot of information on the MIT projects CTSS and Multics, in‐
       cluding  RUNOFF;  it is especially useful for its glossary and the many
       links to historical documents.

       The Unix Archive ⟨http://www.tuhs.org/Archive/⟩, curated  by  the  Unix
       Heritage Society, provides the source code and some binaries of histor‐
       ical  Unices  (including  the source code of some versions of troff and
       its documentation) contributed by their copyright holders.

       Jerry Saltzer’s home page ⟨http://web.mit.edu/Saltzer/www/publications/
       pubs.html⟩ stores some documents using the original  RUNOFF  formatting
       language.

       groff  ⟨http://www.gnu.org/software/groff⟩,  GNU  roff’s web site, pro‐
       vides convenient access to groff’s source code repository, bug tracker,
       and mailing lists (including archives and the subscription interface).

   Historical roff documentation
       Many AT&T troff documents are available online, and  can  be  found  at
       Ralph Corderoy’s site (see above) or via Internet search.

       Of  foremost significance are two mentioned in section “History” above,
       describing the language and its device‐independent implementation,  re‐
       spectively.

       “Troff  User’s  Manual” by Joseph F. Ossanna, 1976 (revised by Brian W.
       Kernighan, 1992), AT&T Bell Laboratories  Computing  Science  Technical
       Report No. 54.

       “A Typesetter‐independent TROFF” by Brian W. Kernighan, 1982, AT&T Bell
       Laboratories Computing Science Technical Report No. 97.

       You  can  obtain  many  relevant  Bell  Labs  papers  in PDF from Bernd
       Warken’s  “roff  classical”  GitHub   repository   ⟨https://github.com/
       bwarken/roff_classical.git⟩.

   Manual pages
       As  a system of multiple components, a roff system potentially has many
       man pages, each describing an aspect of it.  Unfortunately, there is no
       consistent naming scheme for these pages among the different  roff  im‐
       plementations.

       For  GNU  roff, the groff(1) man page enumerates all man pages distrib‐
       uted with the system, and individual pages frequently refer to external
       resources as well as manuals distributed with groff  on  a  variety  of
       topics.

       With  other  roffs,  you  are on your own, but troff(1) might be a good
       starting point.

groff 1.23.0                      2 July 2023                          roff(7)