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GROFF(7)	       Miscellaneous Information Manual		      GROFF(7)

       groff - a short reference for the GNU roff language

       The  name  groff	 stands	for GNU	roff and is the	free implementation of
       the roff	type-setting system.  See roff(7) for a	survey and  the	 back-
       ground of the groff system.

       This document gives only	short descriptions of the predefined roff lan-
       guage elements as used in groff.	 Both the classical features  and  the
       groff extensions	are provided.

       Historically,  the roff language	was called troff.  groff is compatible
       with the	classical system and provides proper extensions.  So  in  GNU,
       the  terms  roff,  troff, and groff language could be used as synonyms.
       However troff slightly tends to refer more to  the  classical  aspects,
       whereas	groff  emphasizes  the GNU extensions, and roff	is the general
       term for	the language.

       This file is only a short version of the	complete documentation that is
       found  in the groff info(1) file, which contains	more detailed, actual,
       and concise information.

       The general syntax for writing groff documents is relatively easy,  but
       writing extensions to the roff language can be a	bit harder.

       The roff	language is line-oriented.  There are only two kinds of	lines,
       control lines and text lines.  The control lines	start with  a  control
       character,  by  default	a period "."  or a single quote	"'"; all other
       lines are text lines.

       Control lines represent commands, optionally with arguments.  They have
       the following syntax.  The leading control character can	be followed by
       a command name; arguments, if any, are separated	 by  blanks  from  the
       command name and	among themselves, for example,

	      .command_name arg1 arg2

       For  indentation, any number of space or	tab characters can be inserted
       between the leading control character and the  command  name,  but  the
       control character must be on the	first position of the line.

       Text lines represent the	parts that will	be printed.  They can be modi-
       fied by escape sequences, which are recognized by a  leading  backslash
       `\'.   These  are  in-line or even in-word formatting elements or func-
       tions.  Some of these take arguments separated by  single  quotes  "'",
       others  are regulated by	a length encoding introduced by	an open	paren-
       thesis `(' or enclosed in brackets `[' and `]'.

       The roff	language provides flexible instruments	for  writing  language
       extension,  such	 as  macros.  When interpreting	macro definitions, the
       roff system enters a special operating mode, called the copy mode.

       The copy	mode behavior can be quite tricky, but there  are  some	 rules
       that ensure a safe usage.

       1.     Printable	 backslashes  must  be denoted as \e.  To be more pre-
	      cise, \e represents the current  escape  character.   To	get  a
	      backslash	glyph, use \(rs	or \[rs].

       2.     Double all backslashes.

       3.     Begin all	text lines with	the special non-spacing	character \&.

       This  does not produce the most efficient code, but it should work as a
       first measure.  For better strategies, see  the	groff  info  file  and

       Reading roff source files is easier, just reduce	all double backslashes
       to a single one in all macro definitions.

       The roff	language elements add formatting information to	a  text	 file.
       The  fundamental	 elements  are	predefined commands and	variables that
       make roff a full-blown programming language.

       There are two kinds of roff commands,  possibly	with  arguments.   Re-
       quests are written on a line of their own starting with a dot `.'  or a
       "'", whereas Escape sequences are in-line functions and in-word format-
       ting elements starting with a backslash `\'.

       The  user  can define her own formatting	commands using the de request.
       These commands are called macros, but they are used  exactly  like  re-
       quests.	 Macro	packages are pre-defined sets of macros	written	in the
       groff language.	A user's possibilities to create escape	sequences her-
       self is very limited, only special characters can be mapped.

       The  groff  language provides several kinds of variables	with different
       interfaces.  There are pre-defined variables, but the user  can	define
       her own variables as well.

       String  variables  store	character sequences.  They are set with	the ds
       request and retrieved by	the \* escape  sequences.   Strings  can  have

       Register	 variables  can	 store	numerical values, numbers with a scale
       unit, and occasionally string-like objects.  They are set with  the  nr
       request and retrieved by	the \n escape sequences.

       Environments  allow the user to temporarily store global	formatting pa-
       rameters	like line length, font size, etc. for later  reuse.   This  is
       done by the ev request.

       Fonts  are  identified  either by a name	or by an internal number.  The
       current font is chosen by the ft	request	or by the \f escape sequences.
       Each  device  has  special fonts, but the following fonts are available
       for all devices.	 R is the standard font	Roman.	B is its bold counter-
       part.   The italic font is called I and is available everywhere,	but on
       text devices it is displayed as an  underlined  Roman  font.   For  the
       graphical  output devices, there	exist constant-width pendants of these
       fonts, CR, CI, and CB.  On text devices,	all characters have a constant
       width anyway.

       Moreover,  there	 are  some advanced roff elements.  A diversion	stores
       information into	a macro	for later usage.  A trap is a positional  con-
       dition  like  a certain number of lines from page top or	in a diversion
       or in the input.	 Some action can be prescribed to be run automatically
       when the	condition is met.

       More  detailed  information and examples	can be found in	the groff info

       There is	a small	set of characters that have a special controlling task
       in certain conditions.

       .      A	 dot  is  only special at the beginning	of a line or after the
	      condition	in the requests	if, ie,	el, and	while.	 There	it  is
	      the control character that introduces a request (or macro).  The
	      special behavior can be delayed by using the \.  escape.	By us-
	      ing  the	cc request, the	control	character can be set to	a dif-
	      ferent character,	making the dot `.'  a non-special character.

	      In all other positions, it just means a dot character.  In  text
	      paragraphs,  it is advantageous to start each sentence at	a line
	      of its own.

       '      The single quote has two controlling tasks.  At the beginning of
	      a	 line  and  in the conditional requests	it is the non-breaking
	      control character.  That means that it introduces	a request like
	      the  dot,	 but  with  the	 additional property that this request
	      doesn't cause a linebreak.  By using the c2  request,  the  non-
	      break control character can be set to a different	character.

	      As  a second task, it is the most	commonly used argument separa-
	      tor in some functional escape sequences (but any pair of charac-
	      ters  not	 part  of the argument will work).  In all other posi-
	      tions, it	denotes	the  single  quote  or	apostrophe  character.
	      Groff  provides  a printable representation with the \(cq	escape

       "      The double quote is  used	 to  enclose  arguments	 in  requests,
	      macros,  and strings.  In	the ds and as requests,	a leading dou-
	      ble quote	in the argument	will be	stripped  off,	making	every-
	      thing else afterwards the	string to be defined (enabling leading
	      whitespace).  The	escaped	double quote \"	introduces a  comment.
	      Otherwise, it is not special.  Groff provides a printable	repre-
	      sentation	with the \(dq escape sequence.

       \      The backslash usually introduces an escape sequence (this	can be
	      changed  with  the ec request).  A printed version of the	escape
	      character	is the \e escape; a backslash glyph can	be obtained by

       (      The  open	 parenthesis  is only special in escape	sequences when
	      introducing an escape name or argument consisting	of exactly two
	      characters.   In	groff, this behavior can be replaced by	the []

       [      The opening bracket is only special in groff  escape  sequences;
	      there  it	is used	to introduce a long escape name	or long	escape
	      argument.	 Otherwise, it is non-special, e.g. in macro calls.

       ]      The closing bracket is only special in groff  escape  sequences;
	      there  it	terminates a long escape name or long escape argument.
	      Otherwise, it is non-special.

       space  Space characters are only	functional characters.	They  separate
	      the arguments in requests, macros, and strings, and the words in
	      text lines.  They	are subject to groff's horizontal spacing cal-
	      culations.   To get a defined space width, escape	sequences like
	      `\ ' (this is the	escape character followed by a space), \|, \^,
	      or \h should be used.

	      In  text	paragraphs,  newlines mostly behave like space charac-
	      ters.  Continuation lines	can be specified by  an	 escaped  new-
	      line,  i.e., by specifying a backslash `\' as the	last character
	      of a line.

       tab    If a tab character occurs	during text the	 interpreter  makes  a
	      horizontal  jump to the next pre-defined tab position.  There is
	      a	sophisticated interface	for handling tab positions.

       A numerical value is a signed or	unsigned  integer  or  float  with  or
       without	an  appended scaling indicator.	 A scaling indicator is	a one-
       character abbreviation for a unit of measurement.  A number followed by
       a scaling indicator signifies a size value.  By default,	numerical val-
       ues do not have a scaling indicator, i.e., they are normal numbers.

       The roff	language defines the following scaling indicators.

	      c		Centimeter
	      i		Inch
	      P		Pica = 1/6 inch
	      p		Point =	1/72 inch
	      m		Em = the font size in points (width of letter `m')
	      M		100th of an Em
	      n		En = Em/2
	      u		Basic unit for actual output device
	      v		Vertical   line	  space	  in   basic   units	scaled
			point =	1/sizescale  of	 a point (defined in font DESC
	      f		Scale by 65536.

       Numerical expressions are combinations of the numerical values  defined
       above  with  the	 following  arithmetical  operators already defined in
       classical troff.

	      +		Addition
	      -		Subtraction
	      *		Multiplication
	      /		Division
	      %		Modulo
	      =		Equals
	      ==	Equals
	      <		Less than
	      >		Greater	than
	      <=	Less or	equal
	      >=	Greater	or equal
	      &		Logical	and
	      :		Logical	or
	      !		Logical	not
	      (		Grouping of expressions
	      )		Close current grouping

       Moreover, groff added the following  operators  for  numerical  expres-

	      e1>?e2	The maximum of e1 and e2.
	      e1<?e2	The minimum of e1 and e2.
	      (c;e)	Evaluate e using c as the default scaling indicator.

       For details see the groff info file.

       Conditions occur	in tests raised	by the if, ie, and the while requests.
       The following table characterizes the different types of	conditions.

	      N		A numerical expression N yields	true if	its  value  is
			greater	than 0.
	      !N	True if	the value of I is 0.
	      's1's2'	True if	string s1 is identical to string s2.
	      !'s1's2'	True if	string s1 is not identical to string s2.
	      cch	True if	there is a character ch	available.
	      dname	True  if  there	 is a string, macro, diversion,	or re-
			quest called name.
	      e		Current	page number is even.
	      o		Current	page number is odd.
	      mname	True if	there is a color called	name.
	      n		Formatter is nroff.
	      rreg	True if	there is a register named reg.
	      t		Formatter is troff.

       This section provides a short reference for  the	 predefined  requests.
       In groff, request and macro names can be	arbitrarily long.  No bracket-
       ing or marking of long names is needed.

       Most requests take one or more arguments.  The arguments	are  separated
       by  space  characters  (no tabs!); there	is no inherent limit for their
       length or number.  An argument can be enclosed  by  a  pair  of	double
       quotes.	 This  is very handy if	an argument contains space characters,
       e.g., "arg with space" denotes a	single argument.

       Some requests have optional arguments with a different behaviour.   Not
       all  of	these details are outlined here.  Refer	to the groff info file
       and groff_diff(7) for all details.

       In the following	request	specifications,	most argument names were  cho-
       sen  to be descriptive.	Only the following denotations need clarifica-

	      c		denotes	a single character.
	      font	a font either specified	as a font name or a font  num-
	      anything	all  characters	up to the end of the line or within \{
			and \}.
	      n		is a numerical expression that evaluates to an integer
	      N		is  an	arbitrary  numerical expression, signed	or un-
	      +-N	has three meanings depending on	 its  sign,  described

       If  an  expression  defined as +-N starts with a	`+' sign the resulting
       value of	the expression will be added to	an already existing value  in-
       herent  to  the	related	request, e.g. adding to	a number register.  If
       the expression starts with a `-'	the value of the  expression  will  be
       subtracted from the request value.

       Without	a  sign,  N replaces the existing value	directly.  To assign a
       negative	number either prepend 0	or  enclose  the  negative  number  in

   Request Short Reference
       .	 Empty line, ignored.  Useful for structuring documents.
       .\" anything
		 Complete line is a comment.
       .ab string
		 Print string on standard error, exit program.
       .ad	 Begin	line  adjustment  for  output  lines in	current	adjust
       .ad c	 Start line adjustment in mode c (c=l,r,b,n).
       .af register c
		 Assign	format c to register (c=l,i,I,a,A).
       .aln alias register
		 Create	alias name for register.
       .als alias object
		 Create	alias name for request,	string,	 macro,	 or  diversion
       .am macro Append	to macro until .. is encountered.
       .am macro end
		 Append	to macro until .end is called.
       .ami macro
		 Append	 to a macro whose name is contained in the string reg-
		 ister macro until .. is encountered.
       .ami macro end
		 Append	to a macro indirectly.	macro and end are string  reg-
		 isters	whose contents are interpolated	for the	macro name and
		 the end macro,	respectively.
       .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.
       .as stringvar anything
		 Append	anything to stringvar.
       .asciify	diversion
		 Unformat ASCII	characters, spaces, and	some escape  sequences
		 in diversion.
       .as1 stringvar anything
		 Same  as  .as but with	compatibility mode switched off	during
		 string	expansion.
		 Print a backtrace of the input	on stderr.
       .bd font	N
		 Embolden font by N-1 units.
       .bd S font N
		 Embolden Special Font S when current font is font.
       .blm	 Unset the blank line macro.
       .blm macro
		 Set the blank line macro to macro.
       .box	 End current diversion.
       .box macro
		 Divert	to macro, omitting a partially filled line.
       .boxa	 End current diversion.
       .boxa macro
		 Divert	and append to macro, omitting a	partially filled line.
       .bp	 Eject current page and	begin new page.
       .bp +-N	 Eject current page; next page number +-N.
       .br	 Line break.
       .brp	 Break and spread output line.	Same as	\p.
       .break	 Break out of a	while loop.
       .c2	 Reset no-break	control	character to "'".
       .c2 c	 Set no-break control character	to c.
       .cc	 Reset control character to `.'.
       .cc c	 Set control character to c.
       .ce	 Center	the next input line.
       .ce N	 Center	following N input lines.
       .cf filename
		 Copy contents of file filename	unprocessed to	stdout	or  to
		 the diversion.
       .cflags mode c1 c2 ...
		 Treat characters c1, c2, ... according	to mode	number.
       .ch trap	N
		 Change	trap location to N .
       .char c anything
		 Define	character c as string anything.
       .chop object
		 Chop  the  last character off macro, string, or diversion ob-
       .close stream
		 Close the stream.
       .color	 Enable	colors.
       .color N	 If N is zero disable colors, otherwise	enable them.
       .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 N	 Continuous underline in nroff,	like .ul in troff.
       .da	 End current diversion.
       .da macro Divert	and append to macro.
       .de macro Define	or redefine macro until	.. is encountered.
       .de macro end
		 Define	or redefine macro until	.end is	called.
       .de1 macro
		 Same  as  .de but with	compatibility mode switched off	during
		 macro expansion.
       .de1 macro end
		 Same as .de but with compatibility mode switched  off	during
		 macro expansion.
       .defcolor color scheme component
		 Define	 or  redefine  a color with name color.	 scheme	can be
		 rgb, cym, cymk, gray, or grey.	 component can be single  com-
		 ponents  specified  as	fractions in the range 0 to 1 (default
		 scaling indicator f), as a string  of	two-digit  hexadecimal
		 color	components  with  a leading #, or as a string of four-
		 digit hexadecimal components with two leading #.   The	 color
		 default can't be redefined.
       .dei macro
		 Define	 or  redefine  a  macro	whose name is contained	in the
		 string	register macro until ..	is encountered.
       .dei macro end
		 Define	or redefine a macro indirectly.	  macro	 and  end  are
		 string	 registers  whose  contents  are  interpolated for the
		 macro name and	the end	macro, respectively.
       .di	 End current diversion.
       .di macro Divert	to macro .
       .do name	 Interpret .name with compatibility mode disabled.
       .ds stringvar anything
		 Set stringvar to anything.
       .ds1 stringvar anything
		 Same as .ds but with compatibility mode switched  off	during
		 string	expansion.
       .dt N trap
		 Set  diversion	 trap  to  position N (default scaling indica-
		 tor v).
       .ec	 Reset escape character	to `\'.
       .ec c	 Set escape character to c.
       .ecr	 Restore escape	character saved	with .ecs.
       .ecs	 Save current escape character.
       .el anything
		 Else part for if-else (ie) request.
       .em macro The macro will	be run after the end of	input.
       .eo	 Turn off escape character mechanism.
       .ev	 Switch	to previous environment.
       .ev env	 Push down environment number or name env and switch to	it.
       .evc env	 Copy the contents of environment env to the current  environ-
		 ment.	No pushing or popping.
       .ex	 Exit from roff	processing.
       .fam	 Return	to previous font family.
       .fam name Set the current font family to	name.
       .fc	 Disable field mechanism.
       .fc a	 Set field delimiter to	a and pad character to space.
       .fc a b	 Set field delimiter to	a and pad character to b.
       .fchar c	anything
		 Define	fallback character c as	string anything.
       .fi	 Fill output lines.
       .fl	 Flush output buffer.
       .fp n font
		 Mount font on position	n.
       .fp n internal external
		 Mount	font with long external	name to	short internal name on
		 position n.
       .fspecial font s1 s2 ...
		 When the current font is font,	then the  fonts	 s1,  s2,  ...
		 will be special.
       .ft	 Return	to previous font.  Same	as \f[]	or \fP.
       .ft font	 Change	 to  font name or number font; same as \f[font]	escape
       .ftr font1 font2
		 Translate font1 to font2.
       .hc	 Remove	additional hyphenation indicator character.
       .hc c	 Set up	additional hyphenation indicator character c.
       .hcode c1 code1 c2 code2	...
		 Set the hyphenation code of character c1 to code1, that of c2
		 to code2, etc.
       .hla lang Set the current hyphenation language to lang.
       .hlm n	 Set the maximum number	of consecutive hyphenated lines	to n.
       .hpf file Read hyphenation patterns from	file.
       .hpfa file
		 Append	hyphenation patterns from file.
       .hpfcode	file
		 Set input mapping for .hpf.
       .hw words List of words with exceptional	hyphenation.
       .hy N	 Switch	to hyphenation mode N.
       .hym n	 Set  the  hyphenation	margin	to  n (default scaling indica-
		 tor m).
       .hys n	 Set the hyphenation space to n.
       .ie cond	anything
		 If cond then anything else goto .el.
       .if cond	anything
		 If cond then anything;	otherwise do nothing.
       .ig	 Ignore	text until .. is encountered.
       .ig end	 Ignore	text until .end.
       .in	 Change	to previous indent value.
       .in +-N	 Change	indent according to +-N	(default scaling indicator m).
       .it N trap
		 Set an	input-line count trap for the next N lines.
       .itc N trap
		 Same as .it but count lines interrupted with \c as one	line.
       .kern	 Enable	pairwise kerning.
       .kern n	 If n is zero, disable pairwise	kerning, otherwise enable it.
       .lc	 Remove	leader repetition character.
       .lc c	 Set leader repetition character to c.
       .length register	anything
		 Write the length of the string	anything in register.
       .linetabs Enable	line-tabs mode (i.e., calculate	tab positions relative
		 to output line).
       .linetabs n
		 If n is zero, disable line-tabs mode, otherwise enable	it.
       .lf N file
		 Set input line	number to N and	filename to file.
       .lg N	 Ligature mode on if N>0.
       .ll	 Change	to previous line length.
       .ll +-N	 Set  line length according to +-N (default size 6.5i, default
		 scaling indicator m).
       .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 +-N	 Length	of title (default scaling indicator m).
       .mc	 Margin	character off.
       .mc c	 Print	character  c  after  each text line at actual distance
		 from right margin.
       .mc c N	 Set margin character to c and distance	to N from right	margin
		 (default scaling indicator m).
       .mk register
		 Mark current vertical position	in register.
       .mso file The  same  as the .so request except that file	is searched in
		 the tmac directories.
       .na	 No output-line	adjusting.
       .ne	 Need a	one-line vertical space.
       .ne N	 Need N	vertical space (default	scaling	indicator v).
       .nf	 No filling or adjusting of output-lines.
       .nh	 No hyphenation.
       .nm	 Number	mode off.
       .nm +-N [M [S [I]]]
		 In line number	mode, set number, multiple, spacing,  and  in-
       .nn	 Do not	number next line.
       .nn N	 Do not	number next N lines.
       .nop anything
		 Always	execute	anything.
       .nr register +-N	M
		 Define	or modify register using +-N with auto-increment M.
       .nroff	 Make the built-in condition n true and	t false.
       .ns	 Turn no-space mode on.
       .nx	 Immediately jump to end of current file.
       .nx filename
		 Next file.
       .open stream filename
		 Open  register	 filename for writing and associate the	stream
		 named register	stream with it.
       .opena stream filename
		 Like .open but	append to it.
       .os	 Output	vertical distance that was saved by the	sv request.
       .output string
		 Emit string directly to intermediate output, allowing leading
		 whitespace  if	 string	 starts	with " (which will be stripped
       .pc	 Reset page number character to	`%'.
       .pc c	 Page number character.
       .pi program
		 Pipe output to	program	(nroff only).
       .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 indicator v).
       .pm	 Print macro names and sizes (number of	blocks of 128 bytes).
       .pm t	 Print	only  total  of	 sizes	of macros (number of 128 bytes
       .pn +-N	 Next page number N.
       .pnr	 Print the names and contents of all currently defined	number
		 registers on stderr.
       .po	 Change	 to  previous page offset.  The	current	page offset is
		 available in register .o.
       .po +-N	 Page offset N.
       .ps	 Return	to previous point-size.
       .ps +-N	 Point size; same as \s[+-N].
       .psbb filename
		 Get the bounding box of a PostScript image filename.
       .pso command
		 This behaves like the so request except that input comes from
		 the standard output of	command.
       .ptr	 Print the names and positions of all traps (not including in-
		 put line traps	and diversion traps) on	stderr.
       .pvs	 Change	to previous post-vertical line spacing.
       .pvs +-N	 Change	post-vertical line spacing according to	 +-N  (default
		 scaling indicator p).
       .rchar c1 c2 ...
		 Remove	the definitions	of characters c1, c2, ...
       .rd prompt
		 Read insertion.
       .return	 Return	from a macro.
       .rj n	 Right justify the next	n input	lines.
       .rm name	 Remove	request, macro,	or string name.
       .rn old new
		 Rename	request, macro,	or string old to new.
       .rnn reg1 reg2
		 Rename	register reg1 to reg2.
       .rr register
		 Remove	register.
       .rs	 Restore spacing; turn no-space	mode off.
       .rt +-N	 Return	 (upward only) to marked vertical place	(default scal-
		 ing indicator v).
       .shc	 Reset soft hyphen character to	\(hy.
       .shc c	 Set the soft hyphen character to c.
       .shift n	 In a macro, shift the arguments by n positions.
       .sizes s1 s2 ...	sn [0]
		 Set available font sizes similar to the sizes	command	 in  a
		 DESC file.
       .so filename
		 Include source	file.
       .sp	 Skip one line vertically.
       .sp N	 Space	vertical  distance N up	or down	according to sign of N
		 (default scaling indicator v).
       .special	s1 s2 ...
		 Fonts s1, s2, etc. are	special	and will be searched for char-
		 acters	not in the current font.
		 Toggle	 the  spread  warning  on and off without changing its
       .spreadwarn limit
		 Emit a	warning	if each	space in an output line	is widened  by
		 limit or more (default	scaling	indicator m).
       .ss N	 Space-character  size	set  to	 N/12 of the spacewidth	in the
		 current font.
       .ss N M	 Space-character size set to N/12 and sentence space size  set
		 to M/12 of the	spacewidth in the current font (=1/3 em).
       .sty n style
		 Associate style with font position n.
       .substring xx n1	n2
		 Replace the string named xx with the substring	defined	by the
		 indices n1 and	n2.
       .sv	 Save 1v of vertical space.
       .sv N	 Save the vertical distance N for later	 output	 with  os  re-
       .sy command-line
		 Execute program command-line.
       .ta T N	 Set  tabs  after  every position that is a multiple of	N (de-
		 fault scaling indicator m).
       .ta n1 n2 ... nn	T r1 r2	... rn
		 Set tabs at positions n1, n2,	...,  nn,  then	 set  tabs  at
		 nn+r1,	 nn+r2,	 ...,  nn+rn, then at nn+rn+r1,	nn+rn+r2, ...,
		 nn+rn+rn, and so on.
       .tc	 Remove	tab repition character.
       .tc c	 Set tab repetition character to c.
       .ti +-N	 Temporary indent next line (default scaling indicator m).
       .tkf font s1 n1 s2 n2
		 Enable	track kerning for font.
       .tl 'left'center'right'
		 Three-part title.
       .tm anything
		 Print anything	on terminal (UNIX standard message output).
       .tm1 anything
		 Print anything	on terminal (UNIX  standard  message  output),
		 allowing  leading whitespace if anything starts with "	(which
		 will be stripped off).
       .tmc anything
		 Similar to .tm1 without emitting a final newline.
       .tr abcd...
		 Translate a to	b, c to	d, etc.	on output.
       .trf filename
		 Transparently output the contents of file filename.
       .trin abcd...
		 This is the same as the tr request except  that  the  asciify
		 request will use the character	code (if any) before the char-
		 acter translation.
       .trnt abcd...
		 This is the same as the tr request except that	 the  transla-
		 tions	do  not	apply to text that is transparently throughput
		 into a	diversion with \!.
       .troff	 Make the built-in condition t true and	n false.
       .uf font	 Underline font	set to font (to	be switched to by .ul).
       .ul N	 Underline (italicize in troff)	N input	lines.
       .unformat diversion
		 Unformat space	characters and tabs, preserving	font  informa-
		 tion in diversion.
       .vpt n	 Enable	vertical position traps	if n is	non-zero, disable them
       .vs	 Change	to previous vertical base line spacing.
       .vs +-N	 Set vertical base line	 spacing  according  to	 +-N  (default
		 scaling indicator p).	Default	value is 12p.
       .warn n	 Set warnings code to n.
       .warnscale si
		 Set scaling indicator used in warnings	to si.
       .wh N	 Remove	(first)	trap at	position N.
       .wh N trap
		 Set location trap; negative means from	page bottom.
       .while cond anything
		 While condition cond is true, accept anything as input.
       .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

       Besides these standard groff requests, there  might  be	further	 macro
       calls.	They  can  originate  from a macro package (see	roff(7)	for an
       overview) or from a preprocessor.

       Preprocessor macros are easy to be recognized.  They enclose their code
       into a pair of characteristic macros.

		      |preprocessor | start macro |  end macro |
		      |	   eqn	    |	  .PS	  |    .PE     |
		      |	   grap	    |	  .G1	  |    .G2     |
		      |	   grn	    |	  .GS	  |    .GE     |
		      |	   pic	    |	  .PS	  |    .PE     |
		      |	  refer	    |	  .R1	  |    .R2     |
		      |	  soelim    |	 none	  |    none    |
		      |	   tbl	    |	  .TS	  |    .TE     |
       Escape  sequences are in-line language elements usually introduced by a
       backslash `\' and followed by an	escape name and	 sometimes  by	a  re-
       quired  argument.  Input	processing is continued	directly after the es-
       caped character or the argument resp. without an	intervening separation
       character.   So	there must be a	way to determine the end of the	escape
       name and	the end	of the argument.

       This is done by enclosing names (escape name and	 arguments  consisting
       of a variable name) by a	pair of	brackets [name]	and constant arguments
       (number expressions and characters) by apostrophes  (ASCII  0x27)  like

       There  are  abbreviations  for short names.  Two	character escape names
       can be specified	by an opening parenthesis like \(xy without a  closing
       counterpart.   And  all	one-character names different from the special
       characters `[' and `(' can even be specified without a  marker  in  the
       form \c.

       Constant	 arguments  of	length 1 can omit the marker apostrophes, too,
       but there is no two-character analogue.

       While 1-character escape	sequences are mainly used  for	in-line	 func-
       tions  and  system  related  tasks, the 2-letter	names following	the \(
       construct are used for special characters predefined by the  roff  sys-
       tem.   Escapes sequences	with names of more than	two characters \[name]
       denote user defined named characters (see the char request).

   Single Character Escapes
       \"     Beginning	of a comment.  Everything up to	the end	of the line is
       \#     Everything  up  to  and  including  the next newline is ignored.
	      This is interpreted in copy mode.	 This is like \"  except  that
	      the terminating newline is ignored as well.
       \*s    The  string  stored in the string	variable with 1-character name
       \*(st  The string stored	in the string variable with  2-character  name
       \*[stringvar arg1 arg2 ...]
	      The  string  stored in the string	variable with arbitrary	length
	      name stringvar, taking arg1, arg2, ... as	arguments.
       \$0    The name by which	the current macro was invoked.	 The  als  re-
	      quest can	make a macro have more than one	name.
       \$x    Macro  or	 string	 argument  with	1-place	number x, where	x is a
	      digit between 1 and 9.
       \$(xy  Macro or string argument with 2-digit number xy.
	      Macro or string argument with number nexp, where nexp is	a  nu-
	      merical expression evaluating to an integer >=1.
       \$*    In  a  macro  or	string,	the concatenation of all the arguments
	      separated	by spaces.
       \$@    In a macro or string, the	concatenation  of  all	the  arguments
	      with each	surrounded by double quotes, and separated by spaces.
       \\     reduces  to  a single backslash; useful to delay its interpreta-
	      tion as escape character in copy mode.  For  a  printable	 back-
	      slash,  use \e, or even better \[rs], to be independent from the
	      current escape character.
       \'     The acute	accent '; same as \(aa.	 Unescaped: apostrophe,	 right
	      quotation	mark, single quote (ASCII 0x27).
       \`     The  grave accent	`; same	as \(ga.  Unescaped: left quote, back-
	      quote (ASCII 0x60).
       \-     The - sign in the	current	font.
       \.     An uninterpreted dot (period), even at start of line.
       \%     Default optional hyphenation character.
       \!     Transparent line indicator.
	      In a diversion, this will	transparently embed  anything  in  the
	      diversion.   anything is read in copy mode.  See also the	escape
	      sequences	\!  and	\?.
       \space Unpaddable space-size space character (no	line break).
       \0     Digit width.
       \|     1/6 em narrow space character; zero width	in nroff.
       \^     1/12 em half-narrow space	character; zero	width in nroff.
       \&     Non-printable, zero width	character.
       \)     Like \& except that it behaves like a  character	declared  with
	      the  cflags request to be	transparent for	the purposes of	end of
	      sentence recognition.
       \/     Increases	the width of the preceding character so	that the spac-
	      ing  between  that character and the following character will be
	      correct if the following character is a roman character.
       \,     Modifies the spacing of the  following  character	 so  that  the
	      spacing  between that character and the preceding	character will
	      correct if the preceding character is a roman character.
       \~     Unbreakable space	that stretches like a normal inter-word	 space
	      when a line is adjusted.
       \:     Inserts  a  zero-width  break point (similar to \% but without a
	      soft hyphen character).
	      Ignored newline, for continuation	lines.
       \{     Begin conditional	input.
       \}     End conditional input.
       \(sc   The special character with 2-character name sc, see section Spe-
	      cial Characters.
	      The named	character with arbitrary length	name name.
       \a     Non-interpreted leader character.
	      If  anything  is acceptable as a name of a string, macro,	diver-
	      sion, register, environment or font it expands to	1,  and	 to  0
	      Bracket building function.
	      If  anything  is acceptable as a valid numeric expression	it ex-
	      pands to 1, and to 0 otherwise.
       \c     Interrupt	text processing.
	      The character called char; same as \[char],  but	compatible  to
	      other roff versions.
       \d     Forward (down) 1/2 em vertical unit (1/2 line in nroff).
	      Draw  a  graphical element defined by the	characters in charseq;
	      see groff	info file for details.
       \e     Printable	version	of the current escape character.
       \E     Equivalent to an escape character, but  is  not  interpreted  in
       \fF    Change to	font with 1-character name or 1-digit number F.
       \fP    Switch back to previous font.
       \f(fo  Change to	font with 2-character name or 2-digit number fo.
	      Change  to  font with arbitrary length name or number expression
       \f[]   Switch back to previous font.
       \Ff    Change to	font family with 1-character name f.
       \F(fm  Change to	font family with 2-character name fm.
	      Change to	font family with arbitrary length name fam.
       \F[]   Switch back to previous font family.
	      Return format of register	with name reg suitable for  .af.   Al-
	      ternative	forms \g(xy and	\gx.
       \h'N'  Local horizontal motion; move right N (left if negative).
       \H'N'  Set height of current font to N.
	      Mark  horizontal	input  place in	register with arbitrary	length
	      name reg.	 Alternative forms \k(xy and \kx.
       \l'Nc' Horizontal line drawing function (optionally using character c).
       \L'Nc' Vertical line drawing function (optionally using character c).
	      Change to	color color.  Alternative forms	\m(co and \mc.
       \m[]   Switch back to previous color.
	      Change filling color for closed drawn objects  to	 color	color.
	      Alternative forms	\M(co and \Mc.
       \M[]   Switch to	previous fill color.
       \nr    The  numerical  value  stored  in	the register variable with the
	      1-character name r.
       \n(re  The numerical value stored in the	 register  variable  with  the
	      2-character name re.
	      The  numerical  value stored in the register variable with arbi-
	      trary length name	reg.
       \N'n'  Typeset the character with code n	in the current font,  no  spe-
	      cial fonts are searched.	Useful for adding characters to	a font
	      using the	char request.
	      Overstrike characters a, b, c, etc.
       \O0    Disable glyph output.  Mainly for	internal use.
       \O1    Enable glyph output.  Mainly for internal	use.
       \p     Break and	spread output line.
       \r     Reverse 1	em vertical motion (reverse line in nroff).
       \R'name +-n'
	      The same as .nr name +-n.
	      Set the point size to N scaled  points.	Note  the  alternative
	      forms  \s+-[N], \s'+-N', \s+-'N',	\s(+-xy, \s+-(xy, \s+-x.  Same
	      as ps request.
       \S'N'  Slant output N degrees.
       \t     Non-interpreted horizontal tab.
       \u     Reverse (up) 1/2 em vertical motion (1/2 line in nroff).
       \v'N'  Local vertical motion; move down N (up if	negative).
	      The contents of the environment variable env.  Alternative forms
	      \V(xy and	\Vx.
	      The width	of the character sequence string.
       \x'N'  Extra line-space function	(negative before, positive after).
	      Output string as device control function.
	      Output  string  variable	or  macro name uninterpreted as	device
	      control function.	 Alternative forms \Y(xy and \Yx.
       \zc    Print c with zero	width (without spacing).
	      Print anything and then restore the horizontal and vertical  po-
	      sition; anything may not contain tabs or leaders.

       The  escape  sequences \e, \., \", \$, \*, \a, \n, \t, \g, and \newline
       are interpreted in copy mode.

       Escape sequences	starting with \( or \[ do not represent	single charac-
       ter escape sequences, but introduce escape names	with two or more char-

       If a backslash is followed by a character that does  not	 constitute  a
       defined escape sequence the backslash is	silently ignored and the char-
       acter maps to itself.

   Special Characters
       Common special characters are predefined	by  escape  sequences  of  the
       form  \(xy  with	 characters x and y.  Some of these exist in the usual
       font while most of them are only	available in the special font.	 Below
       you'll  find  a selection of the	most important glyphs; a complete list
       can be found in groff_char(7).

	      \(bu   Bullet sign
	      \(co   Copyright
	      \(ct   Cent
	      \(dd   Double dagger
	      \(de   Degree
	      \(dg   Dagger
	      \(rs   Printable double quote
	      \(em   Em-dash
	      \(hy   Hyphen
	      \(rg   Registered	sign
	      \(rs   Printable backslash character
	      \(sc   Section sign
	      \(ul   Underline character
	      \(==   Identical
	      \(>=   Larger or equal
	      \(<=   Less or equal
	      \(!=   Not equal
	      \(->   Right arrow
	      \(<-   Left arrow
	      \(+-   Plus-minus	sign

       Strings are defined by the ds request and can be	retrieved  by  the  \*
       escape sequence.

       Strings	share  their  name  space  with	macros.	 So strings and	macros
       without arguments are roughly equivalent; it  is	 possible  to  call  a
       string  like  a	macro  and  vice-versa,	but this often leads to	unpre-
       dictable	results.  The following	strings	are predefined in groff.

       \*[.T]	 The name of the current output	device as specified by the  -T
		 command line option.

       Registers  are  variables that store a value.  In groff,	most registers
       store numerical values (see section NUMERICAL EXPRESSIONS  above),  but
       some can	also hold a string value.

       Each  register is given a name.	Arbitrary registers can	be defined and
       set with	the request nr register.

       The value stored	in a register can be retrieved by the escape sequences
       introduced by \n.

       Most  useful  are  predefined registers.	 In the	following the notation
       name is used to refer to	a register called register name	to make	 clear
       that we speak about registers.  Please keep in mind that	the \n[] deco-
       ration is not part of the register name.

   Read-only Registers
       The following registers have predefined values that should not be modi-
       fied  by	the user (usually, registers starting with a dot a read-only).
       Mostly, they provide information	on the current settings	or  store  re-
       sults from request calls.

       \n[.$]	 Number	of arguments in	the current macro or string.
       \n[.a]	 Post-line  extra  line-space  most  recently  utilized	 using
       \n[.A]	 Set to	1 in troff if option -A	is used; always	1 in nroff.
       \n[.c]	 Current input line number.
       \n[.C]	 1 if compatibility mode is in effect, 0 otherwise.
       \n[.cdp]	 The depth of the last character added to the current environ-
		 ment.	 It  is	 positive  if  the character extends below the
       \n[.ce]	 The number of lines remaining to be centered, as set  by  the
		 ce request.
       \n[.cht]	 The  height  of the last character added to the current envi-
		 ronment.  It is positive if the character extends  above  the
		 1 if colors are enabled, 0 otherwise.
       \n[.csk]	 The  skew of the last character added to the current environ-
		 ment.	The skew of a character	is how far to the right	of the
		 center	of a character the center of an	accent over that char-
		 acter should be placed.
       \n[.d]	 Current vertical place	in current diversion; equal to	regis-
		 ter register nl.
       \n[.ev]	 The  name  or	number of the current environment (string-val-
       \n[.f]	 Current font number.
       \n[.fam]	 The current font family (string-valued).
       \n[.fn]	 The current (internal)	real font name (string-valued).
       \n[.fp]	 The number of the next	free font position.
       \n[.g]	 Always	1 in GNU troff.	 Macros	should use it to test if  run-
		 ning under groff.
       \n[.h]	 Text base-line	high-water mark	on current page	or diversion.
       \n[.H]	 Available horizontal resolution in basic units.
       \n[.hla]	 The current hyphenation language as set by the	.hla request.
       \n[.hlc]	 The  number  of  immediately preceding	consecutive hyphenated
       \n[.hlm]	 The maximum allowed number of consecutive  hyphenated	lines,
		 as set	by the hlm request.
       \n[.hy]	 The current hyphenation flags (as set by the hy request).
       \n[.hym]	 The current hyphenation margin	(as set	by the hym request).
       \n[.hys]	 The current hyphenation space (as set by the hys request).
       \n[.i]	 Current ident.
       \n[.in]	 The indent that applies to the	current	output line.
       \n[.int]	 Positive if last output line contains \c.
       \n[.kern] 1 if pairwise kerning is enabled, 0 otherwise.
       \n[.l]	 Current line length.
       \n[.lg]	 The current ligature mode (as set by the lg request).
		 The current line-tabs mode (as	set by the linetabs request).
       \n[.ll]	 The line length that applies to the current output line.
       \n[.lt]	 The title length (as set by the lt request).
       \n[.n]	 Length	of text	portion	on previous output line.
       \n[.ne]	 The  amount  of  space	that was needed	in the last ne request
		 that caused a trap to be sprung.  Useful in conjunction  with
		 register .trunc.
       \n[.ns]	 1 if in no-space mode,	0 otherwise.
       \n[.o]	 Current page offset.
       \n[.p]	 Current page length.
       \n[.pn]	 The number of the next	page: either the value set by a	pn re-
		 quest,	or the number of the current page plus 1.
       \n[.ps]	 The current pointsize in scaled points.
       \n[.psr]	 The last-requested pointsize in scaled	points.
       \n[.pvs]	 The current post-vertical line	spacing.
       \n[.rj]	 The number of lines to	be right-justified as set  by  the  rj
       \n[.s]	 Current point size as a decimal fraction.
       \n[.sr]	 The  last requested pointsize in points as a decimal fraction
       \n[.t]	 Distance to the next trap.
       \n[.T]	 Set to	1 if option -T is used.
       \n[.tabs] A string representation of the	current	tab settings  suitable
		 for use as an argument	to the ta request.
		 The  amount  of vertical space	truncated by the most recently
		 sprung	vertical position trap,	or, if the trap	was sprung  by
		 a ne request, minus the amount	of vertical motion produced by
		 .ne.  In other	words, at the point a trap is sprung, it  rep-
		 resents  the  difference  of what the vertical	position would
		 have been but for the trap, and what  the  vertical  position
		 actually  is.	 Useful	 in  conjunction with the register .ne
       \n[.ss]	 The value of the parameters set by the	first argument of  the
		 ss request.
       \n[.sss]	 The value of the parameters set by the	second argument	of the
		 ss request.
       \n[.u]	 Equal to 1 bin	fill mode and 0	in nofill mode.
       \n[.v]	 Current vertical line spacing.
       \n[.V]	 Available vertical resolution in basic	units.
       \n[.vpt]	 1  if vertical	position traps are enabled, 0 otherwise.
       \n[.w]	 Width of previous character.
       \n[.warn] The sum of the	number codes of	the  currently	enabled	 warn-
       \n[.x]	 The major version number.
       \n[.y]	 The minor version number.
       \n[.Y]	 The revision number of	groff.
       \n[.z]	 Name of current diversion.

   Writable Registers
       The following registers can be read and written by the user.  They have
       predefined default values, but these can	be modified for	customizing  a

       \n[%]	 Current page number.
       \n[c.]	 Current input line number.
       \n[ct]	 Character type	(set by	width function \w).
       \n[dl]	 Maximal width of last completed diversion.
       \n[dn]	 Height	of last	completed diversion.
       \n[dw]	 Current day of	week (1-7).
       \n[dy]	 Current day of	month (1-31).
       \n[hours] The number of hours past midnight.  Initialized at start-up.
       \n[hp]	 Current horizontal position at	input line.
       \n[llx]	 Lower	left  x-coordinate  (in	 PostScript  units) of a given
		 PostScript image (set by .psbb).
       \n[lly]	 Lower left y-coordinate (in  PostScript  units)  of  a	 given
		 PostScript image (set by .psbb).
       \n[ln]	 Output	line number.
		 The  number of	minutes	after the hour.	 Initialized at	start-
       \n[mo]	 Current month (1-12).
       \n[nl]	 Vertical position of last printed text	base-line.
       \n[rsb]	 Like register sb, but takes account of	the heights and	depths
		 of characters.
       \n[rst]	 Like register st, but takes account of	the heights and	depths
		 of characters.
       \n[sb]	 Depth of string below base line (generated by width  function
		 The  number  of  seconds  after  the  minute.	Initialized at
       \n[skw]	 Right skip width from the center of the last character	in the
		 \w argument.
		 If greater than 0, the	maximum	number of objects on the input
		 stack.	 If <=0	there is no limit, i.e.,  recursion  can  con-
		 tinue until virtual memory is exhausted.
       \n[ssc]	 The  amount  of  horizontal  space  (possibly	negative) that
		 should	be added to the	 last  character  before  a  subscript
		 (generated by width function \w).
       \n[st]	 Height	of string above	base line (generated by	width function
		 The return value of the system()  function  executed  by  the
		 last sy request.
       \n[urx]	 Upper	right  x-coordinate  (in  PostScript units) of a given
		 PostScript image (set by .psbb).
       \n[ury]	 Upper right y-coordinate (in PostScript  units)  of  a	 given
		 PostScript image (set by .psbb).
       \n[year]	 The current year (year	2000 compliant).
       \n[yr]	 Current  year	minus  1900.   For Y2K compliance use register
		 register year instead.

       The differences of the groff language in	comparison to classical	 troff
       as defined by [CSTR #54]	are documented in groff_diff(7).

       The  groff system provides a compatibility mode,	see groff(1) on	how to
       invoke this.

       Report bugs to the groff	bug mailing list <>.  Include
       a complete, self-contained example that will allow the bug to be	repro-
       duced, and say which version of groff you are using.

       Copyright (C) 2000, 2001, 2002 Free Software Foundation,	Inc.

       This document is	distributed under the terms of the FDL (GNU Free Docu-
       mentation  License)  version  1.1 or later.  You	should have received a
       copy of the FDL on your system, it is also available on-line at the GNU
       copyleft	site <>.

       This  document  is  part	 of  groff, the	GNU roff distribution.	It was
       written by Bernd	Warken <>; it is	maintained  by	Werner
       Lemberg <>.

       The  main  source  of  information  for the groff language is the groff
       info(1) file.  Besides the gory details,	it contains many examples.

	      the usage	of the groff program and pointers to the documentation
	      and availability of the groff system.

	      the  differences	of the groff language as compared to classical
	      roff.  This is the authoritative	document  for  the  predefined
	      language elements	that are specific to groff.

	      the predefined groff characters (glyphs).

	      the specification	of fonts and the DESC file.

	      the  history  of	roff, the common parts shared by all roff sys-
	      tems, and	pointers to further documentation.

       [CSTR #54]
	      Nroff/Troff User's Manual	by Osanna & Kernighan <http://> -- the bible for classical troff.

Groff Version 1.18.1	       18 February 2023			      GROFF(7)


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