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GROFF_OUT(5)                           File Formats Manual                           GROFF_OUT(5)

NAME
       groff_out - groff intermediate output format

DESCRIPTION
       This manual page describes the intermediate output format of the GNU roff(7) text process-
       ing system groff(1).  This output is produced by a run of the GNU  troff(1)  program.   It
       contains  already  all  device-specific  information,  but it is not yet fed into a device
       postprocessor program.

       As the GNU roff processor groff(1) is a wrapper program around  troff  that  automatically
       calls  a  postprocessor,  this output does not show up normally.  This is why it is called
       intermediate within the groff system.  The groff program provides the option -Z to inhibit
       postprocessing, such that the produced intermediate output is sent to standard output just
       like calling troff manually.

       In this document, the term troff output describes what is output by the GNU troff program,
       while  intermediate output refers to the language that is accepted by the parser that pre-
       pares this output for the postprocessors.  This parser is smarter on whitespace and imple-
       ments obsolete elements for compatibility, otherwise both formats are the same.  Both for-
       mats can be viewed directly with gxditview(1).

       The main purpose of the intermediate output concept is to facilitate  the  development  of
       postprocessors by providing a common programming interface for all devices.  It has a lan-
       guage of its own that is completely different from the groff(7) language.  While the groff
       language is a high-level programming language for text processing, the intermediate output
       language is a kind of low-level assembler language by specifying all positions on the page
       for writing and drawing.

       The  pre-groff roff versions are denoted as classical troff.  The intermediate output pro-
       duced by groff is fairly readable, while classical troff output was hard to understand be-
       cause of strange habits that are still supported, but not used any longer by GNU troff.

LANGUAGE CONCEPTS
       During  the run of troff, the roff input is cracked down to the information on what has to
       be printed at what position on the intended device.  So the language of  the  intermediate
       output  format  can  be quite small.  Its only elements are commands with or without argu-
       ments.  In this document, the term "command" always refers to the intermediate output lan-
       guage,  never  to  the roff language used for document formatting.  There are commands for
       positioning and text writing, for drawing, and for device controlling.

   Separation
       Classical troff output had strange requirements on whitespace.  The groff  output  parser,
       however,  is smart about whitespace by making it maximally optional.  The whitespace char-
       acters, i.e., the tab, space, and newline characters, always have a  syntactical  meaning.
       They  are  never printable because spacing within the output is always done by positioning
       commands.

       Any sequence of space or tab characters is treated as a single syntactical space.  It sep-
       arates  commands and arguments, but is only required when there would occur a clashing be-
       tween the command code and the arguments without the space.  Most often, this happens when
       variable  length command names, arguments, argument lists, or command clusters meet.  Com-
       mands and arguments with a known, fixed length need not be separated by syntactical space.

       A line break is a syntactical element, too.  Every command argument  can  be  followed  by
       whitespace,  a  comment, or a newline character.  Thus a syntactical line break is defined
       to consist of optional syntactical space that is optionally followed by a comment,  and  a
       newline character.

       The  normal  commands, those for positioning and text, consist of a single letter taking a
       fixed number of arguments.  For historical reasons, the parser  allows  stacking  of  such
       commands  on  the  same line, but fortunately, in groff intermediate output, every command
       with at least one argument is followed by a line break, thus providing excellent readabil-
       ity.

       The  other commands -- those for drawing and device controlling -- have a more complicated
       structure; some recognize long command names, and some take a  variable  number  of  argu-
       ments.   So  all  D and x commands were designed to request a syntactical line break after
       their last argument.  Only one command, 'x X' has an argument that can stretch  over  sev-
       eral  lines,  all  other commands must have all of their arguments on the same line as the
       command, i.e., the arguments may not be split by a line break.

       Empty lines, i.e., lines containing only space and/or a  comment,  can  occur  everywhere.
       They are just ignored.

   Argument Units
       Some commands take integer arguments that are assumed to represent values in a measurement
       unit, but the letter for the corresponding scale indicator is not written with the  output
       command arguments; see groff(7) and Groff: The GNU Implementation of troff, the groff Tex-
       info manual, for more on this topic.  Most commands assume the scale indicator u, the  ba-
       sic  unit  of  the  device, some use z, the scaled point unit of the device, while others,
       such as the color commands expect plain integers.  Note that these  scale  indicators  are
       relative  to  the  chosen device.  They are defined by the parameters specified in the de-
       vice's DESC file; see groff_font(5).

       Note that single characters can have the eighth bit set, as can the  names  of  fonts  and
       special  characters  (this is, glyphs).  The names of glyphs and fonts can be of arbitrary
       length.  A glyph that is to be printed will always be in the current font.

       A string argument is always terminated by the next whitespace character  (space,  tab,  or
       newline);  an  embedded # character is regarded as part of the argument, not as the begin-
       ning of a comment command.  An integer argument is already terminated  by  the  next  non-
       digit  character,  which  then  is regarded as the first character of the next argument or
       command.

   Document Parts
       A correct intermediate output document consists of two parts, the prologue and the body.

       The task of the prologue is to set the general device parameters using three exactly spec-
       ified  commands.  The groff prologue is guaranteed to consist of the following three lines
       (in that order):

              x T device
              x res n h v
              x init

       with the arguments set as outlined in subsection "Device Control  Commands"  below.   How-
       ever,  the  parser for the intermediate output format is able to swallow additional white-
       space and comments as well.

       The body is the main section for processing the document data.  Syntactically, it is a se-
       quence of any commands different from the ones used in the prologue.  Processing is termi-
       nated as soon as the first x stop command is encountered; the last line of any  groff  in-
       termediate output always contains such a command.

       Semantically, the body is page oriented.  A new page is started by a p command.  Position-
       ing, writing, and drawing commands are always done within the current page, so they cannot
       occur  before the first p command.  Absolute positioning (by the H and V commands) is done
       relative to the current page, all other positioning is done relative to the current  loca-
       tion within this page.

COMMAND REFERENCE
       This section describes all intermediate output commands, the classical commands as well as
       the groff extensions.

   Comment Command
       #anything<end-of-line>
              A comment.  Ignore any characters from the # character up to the next newline char-
              acter.

       This command is the only possibility for commenting in the intermediate output.  Each com-
       ment can be preceded by arbitrary syntactical space; every command can be terminated by  a
       comment.

   Simple Commands
       The commands in this subsection have a command code consisting of a single character, tak-
       ing a fixed number of arguments.  Most of them are commands for positioning and text writ-
       ing.  These commands are smart about whitespace.  Optionally, syntactical space can be in-
       serted before, after, and between the command letter and its arguments.  All of these com-
       mands  are  stackable,  i.e., they can be preceded by other simple commands or followed by
       arbitrary other commands on the same line.  A separating syntactical space is only  neces-
       sary  when  two  integer  arguments  would  clash or if the preceding argument ends with a
       string argument.

       C xxx<white-space>
              Print a glyph (special character) named xxx.  The  trailing  syntactical  space  or
              line  break  is  necessary  to allow glyph names of arbitrary length.  The glyph is
              printed at the current print position; the glyph's size is read from the font file.
              The print position is not changed.

       c c    Print  glyph  with  single-letter name c at the current print position; the glyph's
              size is read from the font file.  The print position is not changed.

       f n    Set font to font number n (a non-negative integer).

       H n    Move right to the absolute vertical position n (a  non-negative  integer  in  basic
              units u) relative to left edge of current page.

       h n    Move  n  (a  non-negative  integer)  basic  units  u  horizontally  to  the  right.
              [CSTR #54] allows negative values for n also, but groff doesn't use this.

       m color-scheme [component ...]
              Set the color for text (glyphs), line drawing, and the outline of  graphic  objects
              using  different  color  schemes;  the  analogous  command for the filling color of
              graphic objects is DF.  The color components are specified as integer arguments be-
              tween  0  and 65536.  The number of color components and their meaning vary for the
              different color schemes.  These commands are generated by the groff escape sequence
              \m.  No position changing.  These commands are a groff extension.

              mc cyan magenta yellow
                     Set  color  using  the CMY color scheme, having the 3 color components cyan,
                     magenta, and yellow.

              md     Set color to the default color value (black in most  cases).   No  component
                     arguments.

              mg gray
                     Set  color  to the shade of gray given by the argument, an integer between 0
                     (black) and 65536 (white).

              mk cyan magenta yellow black
                     Set color using the CMYK color scheme, having the 4 color  components  cyan,
                     magenta, yellow, and black.

              mr red green blue
                     Set  color  using  the  RGB color scheme, having the 3 color components red,
                     green, and blue.

       N n    Print glyph with index n (an integer, normally non-negative) of the  current  font.
              The print position is not changed.  If -T html or -T xhtml is used, negative values
              are emitted also to indicate an unbreakable space with given width.   For  example,
              N  -193 represents an unbreakable space which has a width of 193u.  This command is
              a groff extension.

       n b a  Inform the device about a line break, but no positioning is done by  this  command.
              In  classical  troff, the integer arguments b and a informed about the space before
              and after the current line to make the  intermediate  output  more  human  readable
              without  performing  any action.  In groff, they are just ignored, but they must be
              provided for compatibility reasons.

       p n    Begin a new page in the outprint.  The page number is set to n.  This page is  com-
              pletely  independent  of  pages formerly processed even if those have the same page
              number.  The vertical position on the outprint is automatically set to 0.  All  po-
              sitioning,  writing,  and drawing is always done relative to a page, so a p command
              must be issued before any of these commands.

       s n    Set point size to n scaled points (this is unit z in GNU troff).   Classical  troff
              used the unit points (p) instead; see section "Compatibility" below.

       t xyz...<white-space>
       t xyz... dummy-arg<white-space>
              Print  a  word,  i.e., a sequence of glyphs with single-letter names x, y, z, etc.,
              terminated by a space character or a line break; an optional second  integer  argu-
              ment  is  ignored  (this  allows  the formatter to generate an even number of argu-
              ments).  The first glyph should be printed at the  current  position,  the  current
              horizontal  position  should then be increased by the width of the first glyph, and
              so on for each glyph.  The widths of the glyph are read from the font file,  scaled
              for the current point size, and rounded to a multiple of the horizontal resolution.
              Special characters (glyphs with names  longer  than  a  single  letter)  cannot  be
              printed  using this command; use the C command for those glyphs.  This command is a
              groff extension; it is only used for devices whose DESC file contains the  tcommand
              keyword; see groff_font(5).

       u n xyz...<white-space>
              Print word with track kerning.  This is the same as the t command except that after
              printing each glyph, the current horizontal position is increased by the sum of the
              width  of  that glyph and n (an integer in basic units u).  This command is a groff
              extension; it is only used for devices whose DESC file contains the  tcommand  key-
              word; see groff_font(5).

       V n    Move  down  to  the  absolute  vertical position n (a non-negative integer in basic
              units u) relative to upper edge of current page.

       v n    Move n basic units u down (n is a non-negative integer).  [CSTR #54]  allows  nega-
              tive values for n also, but groff doesn't use this.

       w      Informs  about  a  paddable whitespace to increase readability.  The spacing itself
              must be performed explicitly by a move command.

   Graphics Commands
       Each graphics or drawing command in the intermediate output starts with the letter D  fol-
       lowed  by  one or two characters that specify a subcommand; this is followed by a fixed or
       variable number of integer arguments that are separated by a single  space  character.   A
       D  command may not be followed by another command on the same line (apart from a comment),
       so each D command is terminated by a syntactical line break.

       troff output follows the classical spacing rules (no space between command and subcommand,
       all  arguments  are  preceded by a single space character), but the parser allows optional
       space between the command letters and makes the space before the first argument  optional.
       As usual, each space can be any sequence of tab and space characters.

       Some  graphics  commands  can take a variable number of arguments.  In this case, they are
       integers representing a size measured in basic units u.  The h arguments stand  for  hori-
       zontal  distances  where  positive  means right, negative left.  The v arguments stand for
       vertical distances where positive means down, negative up.  All these distances  are  off-
       sets relative to the current location.

       Unless  indicated otherwise, each graphics command directly corresponds to a similar groff
       \D escape sequence; see groff(7).

       Unknown D commands are assumed  to  be  device-specific.   Its  arguments  are  parsed  as
       strings; the whole information is then sent to the postprocessor.

       In  the  following  command reference, the syntax element <line-break> means a syntactical
       line break as defined in subsection "Separation" above.

       D~ h1 v1 h2 v2 ... hn vn<line-break>
              Draw B-spline from current position to offset (h1, v1), then to offset (h2, v2)  if
              given,  etc.,  up  to  (hn, vn).  This  command takes a variable number of argument
              pairs; the current position is moved to the terminal point of the drawn curve.

       Da h1 v1 h2 v2<line-break>
              Draw arc from current position to (h1, v1)+(h2, v2) with center at  (h1, v1);  then
              move the current position to the final point of the arc.

       DC d<line-break>
       DC d dummy-arg<line-break>
              Draw  a solid circle using the current fill color with diameter d (integer in basic
              units u) with leftmost point at the current position; then move the  current  posi-
              tion  to the rightmost point of the circle.  An optional second integer argument is
              ignored (this allows the formatter to generate an even number of arguments).   This
              command is a groff extension.

       Dc d<line-break>
              Draw  circle line with diameter d (integer in basic units u) with leftmost point at
              the current position; then move the current position to the rightmost point of  the
              circle.

       DE h v<line-break>
              Draw  a solid ellipse in the current fill color with a horizontal diameter of h and
              a vertical diameter of v (both integers in basic units u) with the  leftmost  point
              at  the  current  position;  then move to the rightmost point of the ellipse.  This
              command is a groff extension.

       De h v<line-break>
              Draw an outlined ellipse with a horizontal diameter of h and  a  vertical  diameter
              of  v (both integers in basic units u) with the leftmost point at current position;
              then move to the rightmost point of the ellipse.

       DF color-scheme [component ...]<line-break>
              Set fill color for solid drawing objects using different color schemes; the  analo-
              gous  command  for  setting  the  color  of text, line graphics, and the outline of
              graphic objects is m.  The color components are specified as integer arguments  be-
              tween  0  and 65536.  The number of color components and their meaning vary for the
              different color schemes.  These commands are generated  by  the  groff  escape  se-
              quences  \D'F ...'  and \M (with no other corresponding graphics commands).  No po-
              sition changing.  This command is a groff extension.

              DFc cyan magenta yellow<line-break>
                     Set fill color for solid drawing objects using the CMY color scheme,  having
                     the 3 color components cyan, magenta, and yellow.

              DFd <line-break>
                     Set  fill  color  for  solid drawing objects to the default fill color value
                     (black in most cases).  No component arguments.

              DFg gray<line-break>
                     Set fill color for solid drawing objects to the shade of gray given  by  the
                     argument, an integer between 0 (black) and 65536 (white).

              DFk cyan magenta yellow black<line-break>
                     Set fill color for solid drawing objects using the CMYK color scheme, having
                     the 4 color components cyan, magenta, yellow, and black.

              DFr red green blue<line-break>
                     Set fill color for solid drawing objects using the RGB color scheme,  having
                     the 3 color components red, green, and blue.

       Df n<line-break>
              The argument n must be an integer in the range -32767 to 32767.

              0<=n<=1000
                     Set  the color for filling solid drawing objects to a shade of gray, where 0
                     corresponds to solid white, 1000 (the default) to solid black, and values in
                     between to intermediate shades of gray; this is obsoleted by command DFg.

              n<0 or n>1000
                     Set the filling color to the color that is currently being used for the text
                     and the outline, see command m.  For example, the command sequence

                            mg 0 0 65536
                            Df -1

                     sets all colors to blue.

              No position changing.  This command is a groff extension.

       Dl h v<line-break>
              Draw line from current position to offset (h, v) (integers in basic units u);  then
              set current position to the end of the drawn line.

       Dp h1 v1 h2 v2 ... hn vn<line-break>
              Draw  a polygon line from current position to offset (h1, v1), from there to offset
              (h2, v2), etc., up to offset (hn, vn), and from there back to  the  starting  posi-
              tion.  For historical reasons, the position is changed by adding the sum of all ar-
              guments with odd index to the actual horizontal position and the even ones  to  the
              vertical  position.  Although this doesn't make sense it is kept for compatibility.
              This command is a groff extension.

       DP h1 v1 h2 v2 ... hn vn<line-break>
              The same macro as the corresponding Dp command with the same arguments, but draws a
              solid polygon in the current fill color rather than an outlined polygon.  The posi-
              tion is changed in the same way as with Dp.  This command is a groff extension.

       Dt n<line-break>
              Set the current line thickness to n (an integer in basic units u) if  n>0;  if  n=0
              select the smallest available line thickness; if n<0 set the line thickness propor-
              tional to the point size (this is the default before the first Dt command was spec-
              ified).   For  historical reasons, the horizontal position is changed by adding the
              argument to the actual horizontal position, while  the  vertical  position  is  not
              changed.  Although this doesn't make sense it is kept for compatibility.  This com-
              mand is a groff extension.

   Device Control Commands
       Each device control command starts with the letter x followed by a  space  character  (op-
       tional or arbitrary space/tab in groff) and a subcommand letter or word; each argument (if
       any) must be preceded by a syntactical space.  All x commands are terminated by a  syntac-
       tical line break; no device control command can be followed by another command on the same
       line (except a comment).

       The subcommand is basically a single letter, but to increase readability, it can be  writ-
       ten  as  a  word,  i.e.,  an  arbitrary sequence of characters terminated by the next tab,
       space, or newline character.  All characters of the subcommand word but the first are sim-
       ply  ignored.  For example, troff outputs the initialization command x i as x init and the
       resolution command x r as x res.  But writings like x i_like_groff and x roff_is_groff are
       accepted as well to mean the same commands.

       In  the  following,  the syntax element <line-break> means a syntactical line break as de-
       fined in subsection "Separation" above.

       xF name<line-break>
              (Filename control command)
              Use name as the intended name for the current file in error reports.  This is  use-
              ful for remembering the original file name when groff uses an internal piping mech-
              anism.  The input file is not changed by this command.  This command is a groff ex-
              tension.

       xf n s<line-break>
              (font control command)
              Mount font position n (a non-negative integer) with font named s (a text word); see
              groff_font(5).

       xH n<line-break>
              (Height control command)
              Set character height to n (a positive integer in scaled points z).  Classical troff
              used the unit points (p) instead; see section "Compatibility" below.

       xi <line-break>
              (init control command)
              Initialize device.  This is the third command of the prologue.

       xp <line-break>
              (pause control command)
              Parsed  but  ignored.   The  classical  documentation  reads  pause  device, can be
              restarted.

       xr n h v<line-break>
              (resolution control command)
              Resolution is n, while h is the minimal horizontal motion, and v the minimal verti-
              cal  motion possible with this device; all arguments are positive integers in basic
              units u per inch.  This is the second command of the prologue.

       xS n<line-break>
              (Slant control command)
              Set slant to n degrees (an integer in basic units u).

       xs <line-break>
              (stop control command)
              Terminates the processing of the current file; issued as the last  command  of  any
              intermediate troff output.

       xt <line-break>
              (trailer control command)
              Generate trailer information, if any.  In groff, this is actually just ignored.

       xT xxx<line-break>
              (Typesetter control command)
              Set  name  of device to word xxx, a sequence of characters ended by the next white-
              space character.  The possible device names coincide with those from the  groff  -T
              option.  This is the first command of the prologue.

       xu n<line-break>
              (underline control command)
              Configure  underlining  of  spaces.   If  n is 1, start underlining of spaces; if n
              is 0, stop underlining of spaces.  This is needed for the cu request in nroff  mode
              and is ignored otherwise.  This command is a groff extension.

       xX anything<line-break>
              (X-escape control command)
              Send  string anything uninterpreted to the device.  If the line following this com-
              mand starts with a + character this line is interpreted as a continuation  line  in
              the  following sense.  The + is ignored, but a newline character is sent instead to
              the device, the rest of the line is sent uninterpreted.  The same  applies  to  all
              following  lines  until  the  first character of a line is not a + character.  This
              command is generated by the groff escape sequence \X.  The line-continuing  feature
              is a groff extension.

   Obsolete Command
       In  classical troff output, emitting a single glyph was mostly done by a very strange com-
       mand that combined a horizontal move and the printing of a glyph.  It didn't have  a  com-
       mand code, but is represented by a 3-character argument consisting of exactly 2 digits and
       a character.

       ddc    Move right dd (exactly two decimal digits) basic units u,  then  print  glyph  with
              single-letter name c.

              In  groff, arbitrary syntactical space around and within this command is allowed to
              be added.  Only when a preceding command on the same line ends with an argument  of
              variable  length a separating space is obligatory.  In classical troff, large clus-
              ters of these and other commands were used, mostly without spaces; this  made  such
              output almost unreadable.

       For  modern high-resolution devices, this command does not make sense because the width of
       the glyphs can become much larger than two decimal digits.  In groff, this  is  only  used
       for  the  devices X75, X75-12, X100, and X100-12.  For other devices, the commands t and u
       provide a better functionality.

POSTPROCESSING
       The roff postprocessors are programs that have the task to translate the intermediate out-
       put  into  actions that are sent to a device.  A device can be some piece of hardware such
       as a printer, or a software file format suitable for graphical or  text  processing.   The
       groff  system  provides powerful means that make the programming of such postprocessors an
       easy task.

       There is a library function that parses the intermediate output and sends the  information
       obtained to the device via methods of a class with a common interface for each device.  So
       a groff postprocessor must only redefine the methods of this class.  For details, see  the
       reference in section "Files" below.

EXAMPLES
       This section presents the intermediate output generated from the same input for three dif-
       ferent devices.  The input is the sentence hell world fed into groff on the command line.

       o High-resolution device ps

         shell> echo "hell world" | groff -Z -T ps

         x T ps
         x res 72000 1 1
         x init
         p1
         x font 5 TR
         f5
         s10000
         V12000
         H72000
         thell
         wh2500
         tw
         H96620
         torld
         n12000 0
         x trailer
         V792000
         x stop

       This output can be fed into the postprocessor grops(1) to  get  its  representation  as  a
       PostScript file, or gropdf(1) to output directly to PDF.

       o Low-resolution device latin1

         This  is  similar to the high-resolution device except that the positioning is done at a
         minor scale.  Some comments (lines starting with #) were added for  clarification;  they
         were not generated by the formatter.

         shell> "hell world" | groff -Z -T latin1

         # prologue
         x T latin1
         x res 240 24 40
         x init
         # begin a new page
         p1
         # font setup
         x font 1 R
         f1
         s10
         # initial positioning on the page
         V40
         H0
         # write text 'hell'
         thell
         # inform about a space, and do it by a horizontal jump
         wh24
         # write text 'world'
         tworld
         # announce line break, but do nothing because ...
         n40 0
         # ... the end of the document has been reached
         x trailer
         V2640
         x stop

       This output can be fed into the postprocessor grotty(1) to get a formatted text document.

       o Classical style output

         As a computer monitor has a very low resolution compared to modern printers the interme-
         diate output for the X devices can use the jump-and-write command with its 2-digit  dis-
         placements.

         shell> "hell world" | groff -Z -T X100

         x T X100
         x res 100 1 1
         x init
         p1
         x font 5 TR
         f5
         s10
         V16
         H100
         # write text with old-style jump-and-write command
         ch07e07l03lw06w11o07r05l03dh7
         n16 0
         x trailer
         V1100
         x stop

       This  output can be fed into the postprocessor xditview(1x) or gxditview(1) for displaying
       in X.

       Due to the obsolete jump-and-write command, the text clusters in the classical output  are
       almost unreadable.

COMPATIBILITY
       The intermediate output language of the classical troff was first documented in [CSTR #97]
       .  The groff intermediate output format is compatible with this specification  except  for
       the following features.

       o The classical quasi device independence is not yet implemented.

       o The  old  hardware  was very different from what we use today.  So the groff devices are
         also fundamentally different from the ones in classical troff.  For example, the classi-
         cal  PostScript device was called post and had a resolution of 720 units per inch, while
         groff's ps device has a resolution of 72000 units per inch.  Maybe, by implementing some
         rescaling  mechanism  similar to the classical quasi device independence, these could be
         integrated into modern groff.

       o The B-spline command D~ is correctly handled by the intermediate output parser, but  the
         drawing routines aren't implemented in some of the postprocessor programs.

       o The  argument  of  the commands s and x H has the implicit unit scaled point z in groff,
         while classical troff had point (p).  This isn't an incompatibility,  but  a  compatible
         extension,  for  both  units coincide for all devices without a sizescale parameter, in-
         cluding all classical and the  groff  text  devices.   The  few  groff  devices  with  a
         sizescale  parameter  either  did not exist, had a different name, or seem to have had a
         different resolution.  So conflicts with classical devices are very unlikely.

       o The position changing after the commands Dp, DP, and Dt is illogical, but  as  old  ver-
         sions of groff used this feature it is kept for compatibility reasons.

       The differences between groff and classical troff are documented in groff_diff(7).

FILES
       /usr/share/groff/1.22.4/font/devname/DESC
              Device description file for device name.

       src/libs/libdriver/input.cpp
              Defines  the  parser  and postprocessor for the intermediate output.  It is located
              relative to the top directory of the groff source tree.  This parser is the defini-
              tive specification of the groff intermediate output format.

AUTHORS
       James  Clark wrote an early version of this document, which described only the differences
       between ditroff(7)'s output format and that of GNU roff.  The  present  version  was  com-
       pletely rewritten in 2001 by Bernd Warken <groff-bernd.warken-72 AT web.de>.

SEE ALSO
       A reference like groff(7) refers to a manual page; here groff in section 7 of the man page
       documentation system.  To read the example, look up section 7 in your desktop help  system
       or call from the shell prompt

              shell> man 7 groff

       For more details, see man(1).

       groff(1)
              option -Z and further readings on groff.

       groff(7)
              for details of the groff language such as numerical units and escape sequences.

       groff_font(5)
              for details on the device scaling parameters of the DESC file.

       troff(1)
              generates the device-independent intermediate output.

       roff(7)
              for historical aspects and the general structure of roff systems.

       groff_diff(7)
              The differences between the intermediate output in groff and classical troff.

       gxditview(1)
              Viewer for the intermediate output.

       grodvi(1), grohtml(1), grolbp(1), grolj4(1), grops(1), grotty(1)
              the groff postprocessor programs.

       Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner Lemberg, is the pri-
       mary groff manual.  You can browse it interactively with "info groff".

       The classical troff output language is described in two  AT&T  Bell  Labs  CSTR  documents
       available on-line at Bell Labs CSTR site <http://cm.bell-labs.com/cm/cs/cstr.html>.

       [CSTR #97]
              A  Typesetter-independent TROFF by Brian Kernighan is the original and most compre-
              hensive  documentation  on   the   output   language;   see   CSTR   #97   <http://
              cm.bell-labs.com/cm/cs/cstr/97.ps.gz>.

       [CSTR #54]
              The  1992  revision  of  the  Nroff/Troff  User's Manual by J. F. Ossanna and Brian
              Kernighan isn't as comprehensive as [CSTR #97] regarding the output  language;  see
              CSTR #54 <http://cm.bell-labs.com/cm/cs/cstr/54.ps.gz>.

groff 1.22.4                              21 March 2020                              GROFF_OUT(5)

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