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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 processing system.  This output is produced by  a  run  of
       the  GNU  troff(1) program before it is 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  sys-
       tem.   The groff program provides the option -Z to inhibit postprocess-
       ing, 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 prepares this output for the post-
       processors.  This parser is smarter on whitespace and implements  obso-
       lete  elements  for compatibility, otherwise both formats are the same.
       The pre-groff roff versions are denoted as classical troff.

       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 language of its own that  is  com-
       pletely different from the groff(7) language.  While the groff language
       is a high-level programming language for text processing, the  interme-
       diate  output  language  is  a  kind of low-level assembler language by
       specifying all positions on the page for writing and drawing.

       The intermediate output produced by groff  is  fairly  readable,  while
       classical troff output was hard to understand because 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 informa-
       tion on what has to be printed at what position on the intended device.
       So the language of the intermediate output format can be  quite  small.
       Its only elements are commands with or without arguments.  In this doc-
       ument, the term "command" always refers to the intermediate output lan-
       guage,  never to the roff language used for document formatting.  There
       are commands for positioning and text writing,  for  drawing,  and  for
       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 characters, i.e. the tab, space,
       and newline characters, always have a syntactical  meaning.   They  are
       never  printable  because  spacing  within the output is always done by
       positioning commands.

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

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

       The normal commands, those for positioning and text, consist of a  sin-
       gle letter taking a fixed number of arguments.  For historical reasons,
       the parser allows to stack such commands on the same line,  but  fortu-
       nately,  in  groff intermediate output, every command with at least one
       argument is followed by a line break, thus  providing  excellent  read-
       ability.

       The  other commands -- those for drawing and device controlling -- have
       a more complicated structure; some recognize long  command  names,  and
       some take a variable number of arguments.  So all D and x commands were
       designed to request a syntactical line break after their last argument.
       Only  one  command, `x X' has an argument that can stretch over several
       lines, all other commands must have all of their arguments on the  same
       line  as  the command, i.e. the arguments may not be splitted 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 val-
       ues in a measurement unit, but the letter for the  corresponding  scale
       indicator  is  not  written  with  the  output  command  arguments; see
       groff(7) and the groff info file for more on this topic.  Most commands
       assume the scale indicator u, the basic 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 device'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.  The  names  of  characters  and
       fonts  can  be  of arbitrary length.  A character that is to be printed
       will always be in the current font.

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

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

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

              x T device
              x res n h v
              x init

       with the arguments set as outlined in the section Device  Control  Com-
       mands.   But  the  parser for the intermediate output format is able to
       swallow additional whitespace and comments as well.

       The body is the main section for processing the document data.  Syntac-
       tically,  it is a sequence of any commands different from the ones used
       in the prologue.  Processing is terminated as soon as the first  x stop
       command  is encountered; the last line of any groff intermediate output
       always contains such a command.

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

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

   Comment Command
       #anything<&lt;end_of_line>&gt;
              A comment.  Ignore any characters from the # character up to the
              next newline character.

       This command is the only possibility for commenting in the intermediate
       output.  Each comment 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, taking a fixed number of arguments.  Most of them are
       commands  for  positioning  and text writing.  These commands are smart
       about  whitespace.   Optionally,  syntactical  space  can  be  inserted
       before,  after,  and between the command letter and its arguments.  All
       of these commands 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 necessary when two  inte-
       ger  arguments  would  clash  or  if the preceding argument ends with a
       string argument.

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

       c c    Print character c at the current print position; the character'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.  [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 analoguous
              command  for  the  filling  color of graphic objects is DF.  The
              color components are specified as integer  arguments  between  0
              and  65536.   The  number  of color components and their meaning
              vary for the different color schemes.  These commands are gener-
              ated  by  the  groff  escape 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  character  with  index  n (a non-negative integer) of the
              current font.  The print position is not changed.  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 per-
              forming  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 completely 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 positioning,
              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.

       t xxx<white_space>
       t xxx dummy_arg<white_space>
              Print  a word, i.e. a sequence of characters xxx terminated by a
              space character or a line  break;  an  optional  second  integer
              argument  is  ignored  (this allows the formatter to generate an
              even number  of  arguments).   The  first  character  should  be
              printed at the current position, the current horizontal position
              should then be increased by the width of  the  first  character,
              and  so on for each character.  The widths of the characters are
              read from the font file, scaled for the current point size,  and
              rounded  to  a  multiple  of the horizontal resolution.  Special
              characters cannot be printed using this command (use the C  com-
              mand  for named characters).  This command is a groff extension;
              it is only used for devices whose DESC file contains  the  tcom-
              mand keyword; see groff_font(5).

       u n xxx<white_space>
              Print  word  with track kerning.  This is the same as the t com-
              mand except that after printing each character, the current hor-
              izontal  position  is  increased by the sum of the width of that
              character 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 keyword; 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).   [54]
              allows negative 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  com-
              mand.

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

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

       Some graphics commands can take a variable  number  of  arguments.   In
       this  case,  they  are  integers  representing a size measured in basic
       units u.  The arguments called h1, h2, ...,  hn  stand  for  horizontal
       distances  where  positive  means  right, negative left.  The arguments
       called v1, v2, ..., vn stand  for  vertical  distances  where  positive
       means  down,  negative up.  All these distances are offsets relative to
       the current location.

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

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

       In  the  following  command  reference, the syntax element &lt;line_break&gt;
       means a syntactical line break as defined in section Separation.

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

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

       DC d<line_break>
       DC d dummy_arg<line_break>
              Draw a solid circle using the current fill color with diameter d
              (integer in basic units u) with leftmost point  at  the  current
              position;  then move the current position to the rightmost point
              of the circle.  An optional second integer argument  is  ignored
              (this  allows  to  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 analoguous command for setting the color  of  text,
              line  graphics,  and  the  outline of graphic objects is m.  The
              color components are specified as integer  arguments  between  0
              and  65536.   The  number  of color components and their meaning
              vary for the different color schemes.  These commands are gener-
              ated  by  the  groff escape sequences \D'F ...'  and \M (with no
              other corresponding graphics commands).  No  position  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 position.  For historical rea-
              sons, the position is changed by adding the sum of all arguments
              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 exten-
              sion.

       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 position is changed in the
              same way as with Dp.  This command is a groff extension.

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

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

       The subcommand is basically a single letter, but to increase  readabil-
       ity, it can be written as a word, i.e. an arbitrary sequence of charac-
       ters terminated by the next tab,  space,  or  newline  character.   All
       characters  of  the  subcommand  word but the first are simply ignored.
       For example, troff outputs the initialization command x i as x init and
       the  resolution command x r as x res.  But writings like x i_like_groff
       and x roff_is_groff resp. are accepted as well to mean  the  same  com-
       mands.

       In  the  following, the syntax element &lt;line_break&gt; means a syntactical
       line break as defined in section Separation.

       xF name<line_break>
              (Filename control command)
              Use name as the intended name for  the  current  file  in  error
              reports.   This is useful for remembering the original file name
              when groff uses an internal piping mechanism.  The input file is
              not changed by this command.  This command is a groff extension.

       xf n s<line_break>
              (font control command)
              Mount font position n (a non-negative integer) with font named s
              (a text word), cf.  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.

       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 vertical motion possible with this device; all argu-
              ments  are positive integers in basic units u per inch.  This is
              the second command of the prologue.

       xS n<line_break>
              (Slant control command)
              Set slant to n (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 actu-
              ally just ignored.

       xT xxx<line_break>
              (Typesetter control command)
              Set name of device to word xxx, a sequence of  characters  ended
              by  the  next  whitespace  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 other-
              wise.  This command is a groff extension.

       xX anything<line_break>
              (X-escape control command)
              Send string anything uninterpreted to the device.  If  the  line
              following  this  command  starts with a + character this line is
              interpreted as a continuation line in the following sense.   The
              +  is  ignored,  but  a newline character is sent instead to the
              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, the writing of a single character was mostly
       done  by a very strange command that combined a horizontal move and the
       printing of a character.  It didn't have a command code, but is  repre-
       sented  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 character c.

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

       For modern high-resolution devices, this command does  not  make  sense
       because  the  width  of  the characters 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  output  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 sys-
       tem provides powerful means that make the programming of such  postpro-
       cessors an easy task.

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

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

       o High-resolution device ps

         shell&gt; echo hell world | groff -Z -T ps

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

       This  output can be fed into the postprocessor grops(1) to get its rep-
       resentation as a PostScript file.

       o Low-resolution device latin1

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

         shell&gt; echo hell world | groff -Z -T latin1

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

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

       o Classical style output

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

         shell&gt; echo hell world | groff -Z -T X100

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

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

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

COMPATIBILITY
       The intermediate output language of the classical troff was first docu-
       mented  in  [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 clas-
         sical troff.  For example, the classical PostScript device was called
         post  and  had  a  resolution of 720 units per inch, while groff's ps
         device has a resolution of 72000 units per inch.   Maybe,  by  imple-
         menting  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 out-
         put  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, including all classi-
         cal and the groff  text  devices.   The  few  groff  devices  with  a
         sizescale  parameter  either  did not exist, had a different name, or
         seem to have had a different resolution.  So conflicts with classical
         devices are very unlikely.

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

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

FILES
       /usr/share/groff/1.18.1/font/devname/DESC
              Device description file for device name.

       &lt;groff_source_dir&gt;/src/libs/libdriver/input.cc
              Defines the parser and postprocessor for the  intermediate  out-
              put.   It  is located relative to the top directory of the groff
              source tree, e.g.  @GROFFSRCDIR@.  This parser is the definitive
              specification of the groff intermediate output format.

SEE ALSO
       A  reference  like groff(7) refers to a manual page; here groff in sec-
       tion 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&gt; 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  sys-
              tems.

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

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

       For a treatment of all aspects of the groff system within a single doc-
       ument,  see  the groff info file.  It can be read within the integrated
       help systems, within emacs(1) or from the shell prompt by
              shell&gt; 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  origi-
              nal and most concise 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.
              Osanna  and  Brian  Kernighan  isn't  as  concise  as [CSTR #97]
              regarding the output language; see CSTR #54 <http://
              cm.bell-labs.com/cm/cs/cstr/54.ps.gz>.

AUTHORS
       Copyright (C) 1989, 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 with this package; it is also available on-line at the
       GNU copyleft site <http://www.gnu.org/copyleft/fdl.html>;.

       This document is part of groff, the GNU roff distribution.  It is based
       on  a  former  version  - published under the GPL - that described only
       parts of the groff extensions of the  output  language.   It  has  been
       rewritten  2002  by Bernd Warken <bwarkenATmayn.de> and is maintained by
       Werner Lemberg <wlATgnu.org>.



Groff Version 1.18.1               Nov  2002                      GROFF_OUT(5)