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       troff [ -abivzCERU ] [ -wname ] [ -Wname ] [ -dcs ]
             [ -ffam ] [ -mname ] [ -nnum ] [ -olist ] [ -rcn ]
             [ -Tname ] [ -Fdir ] [ -Mdir ] [ files... ]

       It  is  possible to have whitespace between a command line
       option and its parameter.


       This manual page describes the GNU version of troff, which
       is  part  of  the groff document formatting system.  It is
       highly compatible with UNIX troff.  Usually it  should  be
       invoked  using the groff command, which will also run pre­
       processors and postprocessors in the appropriate order and
       with the appropriate options.


       -a        Generate  an  ASCII approximation of the typeset

       -b        Print a backtrace with  each  warning  or  error
                 message.   This backtrace should help track down
                 the cause of the error.  The line numbers  given
                 in  the  backtrace  may  not  always be correct:
                 troff's idea of line numbers gets confused by as
                 or am requests.

       -i        Read  the  standard  input  after  all the named
                 input files have been processed.

       -v        Print the version number.

       -wname    Enable warning  name.   Available  warnings  are
                 described  in  the  Warnings  subsection  below.
                 Multiple -w options are allowed.

       -Wname    Inhibit warning name.  Multiple -W  options  are

       -E        Inhibit  all error messages of troff.  Note that
                 this doesn't affect messages output to  standard
                 error  by  macro  packages using the .tm or .tm1

       -z        Suppress formatted output.

       -C        Enable compatibility mode.

       -dname=s  Define c or name to be a string s; c must  be  a
                 one letter name.

                 For  security reasons, these potentially danger­
                 ous requests are disabled  otherwise.   It  will
                 also  add  the  current  directory  to the macro
                 search path.

       -R        Don't load troffrc and troffrc-end.

       -nnum     Number the first page num.

       -olist    Output only pages in list, which is a comma-sep­
                 arated  list  of page ranges; n means print page
                 n, m-n means print every page between m  and  n,
                 -n  means  print  every  page  up to n, n- means
                 print every page from n.  Troff will exit  after
                 printing the last page in the list.

       -rname=n  Set  number register c or name to n; c must be a
                 one character name; n can be any  troff  numeric

       -Tname    Prepare  output for device name, rather than the
                 default ps.

       -Fdir     Search in directory (or directory path) dir  for
                 subdirectories  devname (name is the name of the
                 device) and there for the  DESC  file  and  font
                 files.   dir  is  scanned  before all other font

       -Mdir     Search directory (or  directory  path)  dir  for
                 macro  files.   This is scanned before all other
                 macro directories.


       Only the features not in UNIX troff are described here.

   Long names
       The     names     of     number     registers,      fonts,
       strings/macros/diversions,  special  characters  can be of
       any length. In escape sequences, where you can use (xx for
       a  two  character  name,  you  can use [xxx] for a name of
       arbitrary length:

       \[xxx] Print the special character called xxx.

              Set font xxx.

              Interpolate string xxx.

       the \H escape sequence,  and  those  variants  of  the  \s
       escape  sequence  that  take a numeric expression as their

       For example, suppose sizescale  is  1000;  then  a  scaled
       point  will be equivalent to a millipoint; the request .ps
       10.25 is equivalent to .ps 10.25z and so sets  the  point­
       size  to  10250  scaled  points,  which  is equal to 10.25

       The number register \n[.s] returns the pointsize in points
       as  decimal fraction.  There is also a new number register
       \n[.ps] that returns the pointsize in scaled points.

       It would make no sense to use the z scale indicator  in  a
       numeric  expression whose default scale indicator was nei­
       ther u nor z, and so troff disallows this.   Similarly  it
       would  make no sense to use a scaling indicator other than
       z or u in a numeric expression whose default scale indica­
       tor was z, and so troff disallows this as well.

       There  is  also  new scale indicator s which multiplies by
       the number of units in a scaled point.  So,  for  example,
       \n[.ps]s is equal to 1m.  Be sure not to confuse the s and
       z scale indicators.

   Numeric expressions
       Spaces are permitted in a number expression within  paren­

       M indicates a scale of 100ths of an em.

       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 indica­
              tor.  If c is missing, ignore scaling indicators in
              the evaluation of e.

   New escape sequences
              This  expands to 1 or 0 according as anything is or
              is not acceptable as the name of a  string,  macro,
              diversion,  number  register,  environment or font.
              It will return 0 if anything  is  empty.   This  is
              useful  if  you  want  to lookup user input in some
              sort of associative table.

              This expands to 1 or 0 according as anything is  or
              is  not a valid numeric expression.  It will return
                     .ds } \s0\v'.3m'

              The use of \E ensures that these  definitions  will
              work even if \*{ gets interpreted in copy-mode (for
              example, by being used in a macro argument).

       \N'n'  Typeset the character with code n  in  the  current
              font.   n  can  be  any integer.  Most devices only
              have characters with codes between 0 and  255.   If
              the  current font does not contain a character with
              that code, special fonts will not be searched.  The
              \N escape sequence can be conveniently used on con­
              junction with the char request:

                     .char \[phone] \f(ZD\N'37'

              The code of each character is given in  the  fourth
              column  in  the  font  description  file  after the
              charset command.  It is possible to include unnamed
              characters  in the font description file by using a
              name of ---; the \N escape sequence is the only way
              to use these.

       \R'name ±n'
              This has the same effect as

                     .nr name ±n

       \s±(nn Set the point size to nn points; nn must be exactly
              two digits.

       \s±'n' Set the point size to  n  scaled  points;  n  is  a
              numeric  expression  with a default scale indicator
              of z.

              Interpolate the contents of the  environment  vari­
              able  xxx,  as returned by getenv(3).  \V is inter­
              preted in copy-mode.

              This is approximately  equivalent  to  \X'\*[xxx]'.
              However the contents of the string or macro xxx are
              not interpreted; also it is permitted  for  xxx  to

       \$*    In a macro, the concatenation of all the  arguments
              separated by spaces.

       \$@    In  a macro, the concatenation of all the arguments
              with each surrounded by double  quotes,  and  sepa­
              rated by spaces.

              In  a  macro,  this gives the nn-th or nnn-th argu­
              ment.  Macros can have an unlimited number of argu­

              When  used  in a diversion, this will transparently
              embed anything in the diversion.  anything is  read
              in  copy  mode.  When the diversion is reread, any­
              thing will be interpreted.  anything may  not  con­
              tain newlines; use \! if you want to embed newlines
              in a diversion.  The escape  sequence  \?  is  also
              recognised  in  copy  mode and turned into a single
              internal code; it is this code that terminates any­
              thing.  Thus
                     .nr x 1
                     .di d
                     .nr x 2
                     .di e
                     .nr x 3
                     .di f
                     .nr x 4

              will print 4.

       \/     This increases the width of the preceding character
              so that the spacing between that character and  the
              following  character will be correct if the follow­
              ing character is a roman character.   For  example,
              if  an  italic f is immediately followed by a roman
              right parenthesis, then in many fonts the top right
              portion  of  the f will overlap the top left of the
              right parenthesis  producing  f),  which  is  ugly.
              Inserting  \/  produces f) and avoids this problem.

       \)     Like \& except that it  behaves  like  a  character
              declared  with the cflags request to be transparent
              for the purposes of end of sentence recognition.

       \~     This produces an unbreakable space  that  stretches
              like  a  normal  inter-word  space  when  a line is

       \:     This causes the insertion  of  a  zero-width  break
              point.   It is equal to \% but without insertion of
              a soft hyphen character.

       \#     Everything up to and including the next newline  is
              ignored.   This  is interpreted in copy mode.  This
              is like \" except that \" does not ignore the  ter­
              minating newline.

   New requests
       .aln xx yy
              Create an alias xx for number register object named
              yy.  The new name and the old name will be  exactly
              equivalent.   If yy is undefined, a warning of type
              reg will be generated,  and  the  request  will  be

       .als xx yy
              Create  an  alias xx for request, string, macro, or
              diversion object named yy.  The new  name  and  the
              old  name will be exactly equivalent (it is similar
              to a hard rather than a soft link).  If yy is unde­
              fined, a warning of type mac will be generated, and
              the request will be ignored.  The de, am,  di,  da,
              ds, and as requests only create a new object if the
              name of the macro, diversion or string diversion is
              currently  undefined  or  if  it is defined to be a
              request; normally  they  modify  the  value  of  an
              existing object.

       .am1 xx yy
              Similar  to .am, but compatibility mode is switched
              off during execution.  On entry, the  current  com­
              patibility mode is saved and restored at exit.

       .asciify xx
              This request `unformats' the diversion xx in such a
              way that  ASCII  and  space  characters  (and  some
              escape  sequences) that were formatted and diverted
              into xx will be treated like ordinary input charac­
              ters  when  xx is reread.  Useful for diversions in
              conjunction with the .writem request.   It  can  be
              also used for gross hacks; for example, this


              will set register n to 1.  Note that glyph informa­
              tion (font, font size, etc.) is not preserved;  use
              .unformat instead.

              Print a backtrace of the input stack on stderr.

       .blm xx
              Set  the  blank  line  macro  to xx.  If there is a
              blank line macro, it will be invoked when  a  blank
              line  is  encountered  instead  of  the usual troff

       .box xx
       .boxa xx
              These  requests  are  similar  to  the  di  and  da
              requests with the exception that a partially filled
              line will not become part of the  diversion  (i.e.,
              the  diversion  always  starts with a new line) but
              restored after ending the diversion, discarding the
              partially filled line which possibly comes from the

       .break Break out of a while loop.  See also the while  and
              continue  requests.   Be  sure  not to confuse this
              with the br request.

       .brp   This is the same as \p.

       .cflags n c1 c2...
              Characters c1, c2,...  have  properties  determined
              by n, which is ORed from the following:

              1      the   character  ends  sentences  (initially
                     characters .?! have this property);

              2      lines can be  broken  before  the  character
                     (initially  no  characters  have  this prop­
                     erty); a line will not be broken at a  char­
                     acter  with this property unless the charac­
                     ters on each side both have non-zero hyphen­
                     ation codes.

              4      lines  can  be  broken  after  the character
                     (initially characters  -\(hy\(em  have  this
                     property);  a  line  will not be broken at a
                     character  with  this  property  unless  the
                     characters  on  each side both have non-zero
                     hyphenation codes.

                     tor    in    TeX    (initially    characters
                     "')]*\(dg\(rq have this property).

       .char c string
              Define  character c to be string.  Every time char­
              acter c needs to be printed, string  will  be  pro­
              cessed  in  a  temporary environment and the result
              will be wrapped up into a single object.   Compati­
              bility mode will be turned off and the escape char­
              acter will be set to \ while string is  being  pro­
              cessed.  Any emboldening, constant spacing or track
              kerning will be applied to this object rather  than
              to  individual  characters  in string.  A character
              defined by this request can be  used  just  like  a
              normal character provided by the output device.  In
              particular other characters can be translated to it
              with  the  tr  request;  it  can be made the leader
              character by the lc request; repeated patterns  can
              be  drawn  with  the  character using the \l and \L
              escape sequences; words  containing  the  character
              can  be  hyphenated correctly, if the hcode request
              is used to give the character a  hyphenation  code.
              There  is  a special anti-recursion feature: use of
              character within the character's definition will be
              handled  like  normal  characters  not defined with
              char.  A character definition can be  removed  with
              the rchar request.

       .chop xx
              Chop  the  last  character  off  macro,  string, or
              diversion xx.  This is useful for removing the new­
              line  from  the  end  of  diversions that are to be
              interpolated as strings.

       .close stream
              Close the  stream  named  stream;  stream  will  no
              longer  be  an  acceptable  argument  to  the write
              request.  See the open request.

              Finish the current iteration of a while loop.   See
              also the while and break requests.

       .cp n  If  n  is non-zero or missing, enable compatibility
              mode, otherwise disable it.  In compatibility mode,
              long  names  are not recognised, and the incompati­
              bilities caused by long names do not arise.

       .dei xx yy
              Define macro indirectly.  The following example

                     .ds xx aa

              For example,

                     .do fam T

              would have the same effect as

                     .fam T

              except  that  it  would  work even if compatibility
              mode had been enabled.  Note that the previous com­
              patibility   mode  is  restored  before  any  files
              sourced by xxx are interpreted.

       .ecs   Save current escape character.

       .ecr   Restore escape character saved with ecs.  Without a
              previous  call  to  ecs, `\' will be the new escape

       .evc xx
              Copy the contents of environment xx to the  current
              environment.   No pushing or popping of environents
              will be done.

       .fam xx
              Set the current font family  to  xx.   The  current
              font family is part of the current environment.  If
              xx is missing, switch back to previous font family.
              See  the  description  of  the sty request for more
              information on font families.

       .fspecial f s1 s2...
              When the current font is f, fonts s1, s2,...   will
              be special, that is, they will searched for charac­
              ters not in the current font.  Any fonts  specified
              in the special request will be searched after fonts
              specified in the fspecial request.

       .ftr f g
              Translate font f to g.  Whenever a font named f  is
              referred  to  in  \f escape sequence, or in the ft,
              ul, bd, cs, tkf,  special,  fspecial,  fp,  or  sty
              requests, font g will be used.  If g is missing, or
              equal to f then font f will not be translated.

       .hcode c1 code1 c2 code2...
              Set the hyphenation code of character c1  to  code1
              and  that  of c2 to code2.  A hyphenation code must
              be a single input character (not a special  charac­
              ter) other than a digit or a space.  Initially each
              lower-case letter has a hyphenation code, which  is
              itself,  and  each  upper-case letter has a hyphen­
              with  the  current  environment.  Only lines output
              from an environment count towards the maximum asso­
              ciated  with  that  environment.  Hyphens resulting
              from \% are counted; explicit hyphens are not.

       .hpf file
              Read hyphenation patterns from file; this  will  be
              searched  for  in  the  same  way that name.tmac is
              searched for when the -mname option  is  specified.
              It  should  have the same format as the argument to
              the \patterns primitive in TeX; the letters appear­
              ing  in  this  file  are interpreted as hyphenation
              codes.  A % character in the patterns  file  intro­
              duces  a  comment  that continues to the end of the
              line.  The set of hyphenation patterns  is  associ­
              ated  with  the  current  language  set  by the hla
              request.  The hpf request is usually invoked by the
              troffrc file.

       .hym n Set  the  hyphenation margin to n: when the current
              adjustment mode is not b,  the  line  will  not  be
              hyphenated  if  the  line  is no more than n short.
              The default hyphenation margin is 0.   The  default
              scaling  indicator  for  this  request  is  m.  The
              hyphenation margin is associated with  the  current
              environment.   The  current  hyphenation  margin is
              available in the \n[.hym] register.

       .hys n Set the hyphenation space to n:  when  the  current
              adjustment  mode  is  b don't hyphenate the line if
              the line can be justified by adding no more than  n
              extra  space  to  each  word  space.   The  default
              hyphenation space is 0.  The default scaling  indi­
              cator for this request is m.  The hyphenation space
              is associated with the  current  environment.   The
              current  hyphenation  space  is  available  in  the
              \n[.hys] register.

       .kern n
              If n is non-zero or missing, enable pairwise  kern­
              ing, otherwise disable it.

       .length xx string
              Compute  the  length of string and return it in the
              number  register  xx  (which  is  not   necessarily
              defined before).

       .linetabs n
              If n is non-zero or missing, enable line-tabs mode,
              otherwise disable it (which is  the  default).   In
              line-tabs mode, tab distances are computed relative
              to the (current) output line.  Otherwise  they  are


                     a         b         c

              In line-tabs mode, the same code gives

                     a         b                   c

              Line-tabs mode is associated with the current envi­
              ronment;     the    read-only    number    register
              \n[.linetabs] is set to 1 if in line-tabs mode, and
              0 otherwise.

       .mso file
              The  same  as  the  so  request except that file is
              searched for in the same directories as macro files
              for  the  the  -m command line option.  If the file
              name to be included has the form name.tmac  and  it
              isn't found, mso tries to include tmac.name instead
              and vice versa.

       .nop anything
              Execute anything.  This is similar to `.if 1'.

       .nroff Make the n built-in condition true and the t built-
              in condition false.  This can be reversed using the
              troff request.

       .open stream filename
              Open filename for writing and associate the  stream
              named stream with it.  See also the close and write

       .opena stream filename
              Like open, but if filename  exists,  append  to  it
              instead of truncating it.

       .pnr   Print  the  names  and  contents  of  all currently
              defined number registers on stderr.

       .psbb filename
              Get the bounding box of a  PostScript  image  file­
              name.   This  file must conform to Adobe's Document
              Structuring Conventions; the command  looks  for  a
              %%BoundingBox  comment  to extract the bounding box
              values.  After a successful call,  the  coordinates
              (in  PostScript  units) of the lower left and upper
              right corner can be found in the registers \n[llx],
              \n[lly],  \n[urx],  and  \n[ury], respectively.  If
              some error has occurred, the four registers are set
              to zero.

              Within a macro, return immediately.  No effect oth­

       .rj n  Right justify the next n input lines.   Without  an
              argument  right  justify  the next input line.  The
              number of lines to be right justified is  available
              in  the  \n[.rj]  register.   This  implicitly does
              .ce 0.  The ce request implicitly does .rj 0.

       .rnn xx yy
              Rename number register xx to yy.

       .shc c Set the soft hyphen character to c.  If c is  omit­
              ted,  the  soft hyphen character will be set to the
              default \(hy.  The soft  hyphen  character  is  the
              character  which  will  be  inserted when a word is
              hyphenated at a line break.   If  the  soft  hyphen
              character does not exist in the font of the charac­
              ter immediately preceding a potential break  point,
              then  the  line  will  not be broken at that point.
              Neither  definitions  (specified  with   the   char
              request)  nor  translations  (specified with the tr
              request)  are  considered  when  finding  the  soft
              hyphen character.

       .shift n
              In  a  macro,  shift  the arguments by n positions:
              argument i becomes argument i-n; arguments 1  to  n
              will  no  longer  be  available.   If n is missing,
              arguments will be shifted by 1.  Shifting by  nega­
              tive amounts is currently undefined.

       .special s1 s2...
              Fonts  s1, s2, are special and will be searched for
              characters not in the current font.

       .sty n f
              Associate style f with font  position  n.   A  font
              position  can  be  associated either with a font or
              with a style.  The current font is the index  of  a
              font  position  and  so  is also either a font or a
              style.  When it is a style, the font that is  actu­
              ally used is the font the name of which is the con­
              catenation of the name of the  current  family  and
              the name of the current style.  For example, if the
              current font is 1 and font position 1 is associated
              with style R and the current font family is T, then
              font TR will be used.  If the current font is not a
              style,  then  the  current family is ignored.  When
              length.  If the index value n1 or n2 is negative or
              zero, it will  be  counted  from  the  end  of  the
              string,  going  backwards:  The  last character has
              index 0, the character before  the  last  character
              has index -1, etc.

       .tkf f s1 n1 s2 n2
              Enable  track kerning for font f.  When the current
              font is f the width  of  every  character  will  be
              increased  by an amount between n1 and n2; when the
              current point size is less than or equal to s1  the
              width  will  be increased by n1; when it is greater
              than or equal to s2 the width will be increased  by
              n2; when the point 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 point size.

       .tm1 string
              Similar  to  the tm request, string is read in copy
              mode and written on the standard error, but an ini­
              tial  double  quote  in  string  is stripped off to
              allow initial blanks.

       .tmc string
              Similar to tm1 but without writing a final newline.

       .trf filename
              Transparently output the contents of file filename.
              Each line is output as it would be were it preceded
              by  \!; however, the lines are not subject to copy-
              mode interpretation.  If the file does not end with
              a newline, then a newline will be added.  For exam­
              ple, you can define a macro x containing  the  con­
              tents of file f, using

                     .di x
                     .trf f

              Unlike with the cf request, the file cannot contain
              characters such as NUL that  are  not  legal  troff
              input characters.

       .trnt abcd
              This  is the same as the tr request except that the
              translations do not apply to text that is transpar­
              ently  throughput  into  a  diversion with \!.  For

                     .tr ab
                     .di x
                     \!.tm a

              input tokens as much as  possible,  .unformat  will
              only  handle tabs and spaces between words (usually
              caused by spaces or newlines  in  the  input)  spe­
              cially.   The  former  are  treated as if they were
              input tokens, and the latter are stretchable again.
              Note  that  the  vertical size of lines is not pre­
              served.  Glyph information (font, font size,  space
              width,  etc.)  is  retained.  Useful in conjunction
              with the .box and .boxa requests.

       .vpt n Enable vertical position traps if  n  is  non-zero,
              disable  them  otherwise.   Vertical position traps
              are traps set by the wh or dt requests.  Traps  set
              by  the it request are not vertical position traps.
              The parameter that controls whether vertical  posi­
              tion traps are enabled is global.  Initially verti­
              cal position traps are enabled.

       .warn n
              Control warnings.  n is  the  sum  of  the  numbers
              associated with each warning that is to be enabled;
              all other warnings will be  disabled.   The  number
              associated  with  each  warning  is  listed  in the
              `Warnings' section.  For example, .warn 0 will dis­
              able  all  warnings,  and  .warn 1 will disable all
              warnings except that about missing characters.   If
              n is not given, all warnings will be enabled.

       .while c anything
              While  condition  c  is  true,  accept  anything as
              input; c can be any condition acceptable to  an  if
              request;  anything  can  comprise multiple lines if
              the first line starts with \{  and  the  last  line
              ends  with  \}.   See  also  the break and continue

       .write stream anything
              Write anything to the stream named stream.   stream
              must  previously  have  been the subject of an open
              request.  anything is read in copy mode; a  leading
              " will be stripped.

       .writem stream xx
              Write the contents of the macro or string xx to the
              stream named stream.  stream must  previously  have
              been the subject of an open request.  xx is read in
              copy mode.

   Extended requests
       .cf filename
              When used in a diversion, this will  embed  in  the
              diversion  an object which, when reread, will cause

       .fp n f1 f2
              The  fp  request  has  an  optional third argument.
              This argument gives the external name of the  font,
              which  is  used  for  finding  the font description
              file.  The second argument gives the internal  name
              of  the  font which is used to refer to the font in
              troff after it has been mounted.  If  there  is  no
              third  argument then the internal name will be used
              as the external name.  This feature allows  you  to
              use fonts with long names in compatibility mode.

       .ss m n
              When two arguments are given to the ss request, the
              second argument gives the sentence space size.   If
              the  second  argument  is  not  given, the sentence
              space size will be the same as the word space size.
              Like  the word space size, the sentence space is in
              units of one twelfth of  the  spacewidth  parameter
              for  the  current  font.   Initially  both the word
              space size and the  sentence  space  size  are  12.
              Contrary  to  UNIX  troff,  GNU  troff handles this
              request in nroff mode also; a given value  is  then
              rounded  down  to  the nearest multiple of 12.  The
              sentence space size is used in  two  circumstances:
              if  the  end  of  a sentence occurs at the end of a
              line in fill mode, then both  an  inter-word  space
              and  a  sentence space will be added; if two spaces
              follow the end of a sentence in  the  middle  of  a
              line,  then  the  second  space  will be a sentence
              space.  Note that the behaviour of UNIX troff  will
              be  exactly that exhibited by GNU troff if a second
              argument is never given to the ss request.  In  GNU
              troff, as in UNIX troff, you should always follow a
              sentence with either a newline or two spaces.

       .ta n1 n2...nn T r1 r2...rn
              Set tabs at positions n1, n2,..., nn and  then  set
              tabs  at  nn+r1,  nn+r2,....,  nn+rn  and  then  at
              nn+rn+r1, nn+rn+r2,..., nn+rn+rn, and so  on.   For

                     .ta T .5i

              will set tabs every half an inch.

   New number registers
       The following read-only registers are available:

       \n[.C] 1  if compatibility mode is in effect, 0 otherwise.

              The skew of the last character added to the current
              environment.  The skew of a character is how far to
              the  right  of the center of a character the center
              of an accent over that character should be  placed.

              The  name  or  number  of  the current environment.
              This is a string-valued register.

              The current font family.  This is  a  string-valued

              The number of the next free font position.

       \n[.g] Always  1.   Macros  should  use  this to determine
              whether they are running under GNU troff.

              The current hyphenation language as set by the  hla

              The  number  of  immediately  preceding consecutive
              hyphenated lines.

              The maximum allowed number of  consecutive  hyphen­
              ated lines, as set by the hlm request.

              The  current  hyphenation  flags  (as set by the hy

              The current hyphenation margin (as set by  the  hym

              The  current  hyphenation  space (as set by the hys

              The indent that applies to the current output line.

              Set  to  a  positive  value  if last output line is
              interrupted (i.e., if it contains \c).

              1 if pairwise kerning is enabled, 0 otherwise.
              The title length as set by the lt request.

              The  amount of space that was needed in the last ne
              request that caused a trap to be sprung.  Useful in
              conjunction with the \n[.trunc] register.

              1 if no-space mode is active, 0 otherwise.

              The  number  of the next page: either the value set
              by a pn request, or the number of the current  page
              plus 1.

              The current pointsize in scaled points.

              The last-requested pointsize in scaled points.

              The number of lines to be right-justified as set by
              the rj request.

              The last requested pointsize in points as a decimal
              fraction.  This is a string-valued register.

              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 the ne request.   In
              other words, at the point a trap is sprung, it rep­
              resents the difference of what the  vertical  posi­
              tion would have been but for the trap, and what the
              vertical position actually is.  Useful in  conjunc­
              tion with the \n[.ne] register.

              These  give the values of the parameters set by the
              first and second arguments of the ss request.

              1 if vertical position traps are enabled, 0  other­

              These four registers are set by the  .psbb  request
              and  contain the bounding box values (in PostScript
              units) of a given PostScript image.

       The following read/write  registers  are  set  by  the  \w
       escape sequence:

              Like  the st and sb registers, but takes account of
              the heights and depths of characters.

              The amount of horizontal space (possibly  negative)
              that should be added to the last character before a

              How far to right of the center of the last  charac­
              ter  in  the  \w  argument, the center of an accent
              from a roman font should be placed over that  char­

       Other available read/write number registers are:

       \n[c.] The  current  input line number.  \n[.c] is a read-
              only alias to this register.

       \n[hp] The current horizontal position at input line.

              The return value of the system() function  executed
              by the last sy request.

              If greater than 0, the maximum number of objects on
              the input stack.  If less than or equal to 0, there
              is  no  limit on the number of objects on the input
              stack.  With no limit, recursion can continue until
              virtual memory is exhausted.

              The  current year.  Note that the traditional troff
              number register \n[yr] is the  current  year  minus

       found  in  the  \n[.fp]  register; although troff does not
       enforce this strictly, it will not  allow  a  font  to  be
       mounted  at  a  position whose number is much greater than
       that of any currently used position.

       Interpolating a string does not hide existing macro  argu­
       ments.  Thus in a macro, a more efficient way of doing

              .xx \\$@



       If  the  font  description  file contains pairwise kerning
       information, characters from that  font  will  be  kerned.
       Kerning between two characters can be inhibited by placing
       a \& between them.

       In a string comparison in  a  condition,  characters  that
       appear  at  different  input levels to the first delimiter
       character will not be recognised as the  second  or  third
       delimiters.  This applies also to the tl request.  In a \w
       escape sequence, a character that appears at  a  different
       input  level  to the starting delimiter character will not
       be recognised as the closing  delimiter  character.   When
       decoding  a  macro  argument  that  is delimited by double
       quotes, a character that  appears  at  a  different  input
       level  to  the  starting  delimiter  character will not be
       recognised as the closing delimiter character.  The imple­
       mentation  of \$@ ensures that the double quotes surround­
       ing an argument will appear the same  input  level,  which
       will  be  different  to  the  input  level of the argument
       itself.  In a long escape name ] will not be recognized as
       a  closing  delimiter  except  when  it occurs at the same
       input level as the opening ].  In compatibility  mode,  no
       attention is paid to the input-level.

       There are some new types of condition:

       .if rxxx
              True if there is a number register named xxx.

       .if dxxx
              True  if  there  is  a string, macro, diversion, or
              request named xxx.

       .if cch
              True if there is a character ch  available;  ch  is
              either  an  ASCII  character or a special character
              \(xx or \[xxx]; the condition will also be true  if
              ch has been defined by the char request.

       break          4   In fill mode, lines which could not  be
                          broken  so  that  their length was less
                          than the line length.  This is  enabled
                          by default.

       delim          8   Missing  or  mismatched  closing delim­

       el            16   Use of the el request with no  matching
                          ie request.

       scale         32   Meaningless scaling indicators.

       range         64   Out of range arguments.

       syntax       128   Dubious  syntax in numeric expressions.

       di           256   Use of di or  da  without  an  argument
                          when there is no current diversion.

       mac          512   Use  of  undefined  strings, macros and
                          diversions.  When an undefined  string,
                          macro or diversion is used, that string
                          is automatically defined as empty.  So,
                          in most cases, at most one warning will
                          be given for each name.

       reg         1024   Use  of  undefined  number   registers.
                          When  an  undefined  number register is
                          used, that  register  is  automatically
                          defined  to have a value of 0.  a defi­
                          nition is  automatically  made  with  a
                          value of 0.  So, in most cases, at most
                          one warning will be given for use of  a
                          particular name.

       tab         2048   Inappropriate  use  of a tab character.
                          Either use of a tab character  where  a
                          number  was  expected,  or  use  of tab
                          character in an  unquoted  macro  argu­

       right-brace 4096   Use  of \} where a number was expected.

       missing     8192   Requests that are missing  non-optional

       input      16384   Illegal input characters.

       escape     32768   Unrecognized escape sequences.  When an
                          unrecognized escape sequence is encoun­

       font      131072   Non-existent fonts.  This is enabled by

       ig        262144   Illegal  escapes  in  text ignored with
                          the ig request.  These  are  conditions
                          that  are errors when they do not occur
                          in ignored text.

       There are also names that can be used to refer  to  groups
       of warnings:

       all    All  warnings  except  di,  mac  and  reg.   It  is
              intended that this covers  all  warnings  that  are
              useful with traditional macro packages.

       w      All warnings.

       Long  names cause some incompatibilities.  UNIX troff will


       as defining a string ab with contents cd.   Normally,  GNU
       troff  will  interpret  this  as  a  call of a macro named
       dsabcd.  Also UNIX troff will interpret \*[ or \n[ as ref­
       erences  to  a string or number register called [.  In GNU
       troff, however, this will normally be interpreted  as  the
       start  of  a  long  name.  In compatibility mode GNU troff
       will interpret these things in the  traditional  way.   In
       compatibility  mode,  however,  long  names are not recog­
       nised.  Compatibility mode can be turned on  with  the  -C
       command  line  option,  and  turned  on or off with the cp
       request.  The number register \n[.C] is 1 if compatibility
       mode is on, 0 otherwise.

       GNU  troff  does not allow the use of the escape sequences
       \\|\^\&\}\{\(space)\'\`\-\_\!\%\c  in  names  of  strings,
       macros,  diversions,  number  registers, fonts or environ­
       ments; UNIX troff does.  The \A  escape  sequence  may  be
       helpful  in  avoiding  use  of  these  escape sequences in

       Fractional pointsizes cause one  noteworthy  incompatibil­
       ity.   In  UNIX troff the ps request ignores scale indica­
       tors and so

              .ps 10u

       will set the pointsize to 10 points, whereas in GNU  troff
       it will set the pointsize to 10 scaled points.

       of  the  special  properties that the input character from
       which it was constructed might have had.  For example,

              .di x

       will print \\ in GNU troff;  each  pair  of  input  \s  is
       turned  into  one output \ and the resulting output \s are
       not interpreted as escape characters when they are reread.
       UNIX  troff would interpret them as escape characters when
       they were reread and would end up  printing  one  \.   The
       correct  way  to  obtain  a  printable  \ is to use the \e
       escape sequence: this will always print a single  instance
       of  the current escape character, regardless of whether or
       not it is used in a diversion; it will also work  in  both
       GNU  troff and UNIX troff.  If you wish for some reason to
       store in a diversion  an  escape  sequence  that  will  be
       interpreted  when  the diversion is reread, you can either
       use the traditional \! transparent output facility, or, if
       this is unsuitable, the new \? escape sequence.


              A  colon  separated list of directories in which to
              search for macro files.  troff will  scan  directo­
              ries  given  in  the -M option before these, and in
              standard  directories  (current  directory  if   in
              unsafe mode, home directory, /usr/share/groff/site-
              tmac,                     /usr/lib/groff/site-tmac,
              /usr/share/groff/1.17.2/tmac) after these.

              Default device.

              A  colon  separated list of directories in which to
              search for the devname directory.  troff will  scan
              directories  given  in  the -F option before these,
              and         in         standard         directories
              (/usr/share/groff/1.17.2/font:/usr/lib/font)  after


              Initialization file (called before any other  macro

              Initialization  file  (called after any other macro

       rity reasons (even if the -U option is given).  Use the -M
       command  line  option  or  the GROFF_TMAC_PATH environment
       variable to add these directories to the  search  path  if


       groff(7)  -- This is a short but complete reference of all
       requests, registers, and escapes.

       groff(1), tbl(1),  pic(1),  eqn(1),  refer(1),  soelim(1),
       grn(1),   grops(1),   grodvi(1),   grotty(1),  grohtml(1),
       grolj4(1), groff_font(5), groff_out(5), groff_char(7)

Groff Version 1.17.2    23 September 2003                TROFF(1)

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