Provided by: groff_1.22.3-9_amd64 bug

NAME

       groff_font - format of groff device and font description files

DESCRIPTION

       The  groff  font  format is roughly a superset of the ditroff font format.  The font files
       for device name are stored in a directory devname.  There are two types of file: a  device
       description  file  called  DESC  and for each font F a font file called F.  These are text
       files; unlike the ditroff font format, there is no associated binary format.

   DESC file format
       The DESC file can contain the following types of line as shown below.   Later  entries  in
       the file override previous values.

       Empty lines are ignored.

       charset
              This  line and everything following in the file are ignored.  It is allowed for the
              sake of backwards compatibility.

       family fam
              The default font family is fam.

       fonts n F1 F2 F3 ... Fn
              Fonts F1, ..., Fn are mounted in the font positions m+1, ..., m+n where  m  is  the
              number  of  styles.   This command may extend over more than one line.  A font name
              of 0 causes no font to be mounted on the corresponding font position.

       hor n  The horizontal resolution is n machine units.

       image_generator string
              Needed for grohtml only.  It specifies the program  to  generate  PNG  images  from
              PostScript  input.   Under  GNU/Linux  this  is  usually gs but under other systems
              (notably cygwin) it might be set to another name.

       paperlength n
              The physical vertical dimension of the output medium in machine units.  This  isn't
              used by troff itself but by output devices.  Deprecated.  Use papersize instead.

       papersize string
              Select a paper size.  Valid values for string are the ISO paper types A0–A7, B0–B7,
              C0–C7, D0–D7, DL, and the US paper types letter, legal, tabloid, ledger, statement,
              executive,  com10,  and  monarch.   Case  is not significant for string if it holds
              predefined  paper  types.   Alternatively,  string  can  be  a  file   name   (e.g.
              ‘/etc/papersize’);  if the file can be opened, groff reads the first line and tests
              for the above paper sizes.  Finally, string can be  a  custom  paper  size  in  the
              format  length,width (no spaces before and after the comma).  Both length and width
              must have a unit appended; valid values are ‘i’ for inches,  ‘c’  for  centimeters,
              ‘p’  for  points,  and ‘P’ for picas.  Example: 12c,235p.  An argument which starts
              with a digit is always treated as a custom paper format.  papersize sets  both  the
              vertical and horizontal dimension of the output medium.

              More  than  one  argument can be specified; groff scans from left to right and uses
              the first valid paper specification.

       paperwidth n
              The  physical  horizontal  dimension  of  the  output  medium  in  machine   units.
              Deprecated.   Use papersize instead.  This isn't used by troff itself but by output
              devices.

       pass_filenames
              Make troff tell the driver the source file name being processed.  This is  achieved
              by another tcommand: F filename.

       postpro program
              Use program as the postprocessor.

       prepro program
              Call program as a preprocessor.

       print program
              Use program as the spooler program for printing.  If omitted, the -l and -L options
              of groff are ignored.

       res n  There are n machine units per inch.

       sizes s1 s2 ... sn 0
              This means that the device has fonts at s1, s2, ..., sn scaled points.  The list of
              sizes  must  be  terminated by a 0.  Each si can also be a range of sizes mn.  The
              list can extend over more than one line.

       sizescale n
              The scale factor for point sizes.  By default this has a value of  1.   One  scaled
              point  is  equal to one point/n.  The arguments to the unitwidth and sizes commands
              are given in scaled points.

       styles S1 S2 ... Sm
              The first m font positions are associated with styles S1, ..., Sm.

       tcommand
              This means that the postprocessor can handle the t and u output commands.

       unicode
              Indicate that the output device supports the complete Unicode  repertoire.   Useful
              only for devices which produce character entities instead of glyphs.

              If unicode is present, no charset section is required in the font description files
              since the Unicode handling built into groff is used.  However, if there are entries
              in  a  charset  section,  they  either  override  the  default  mappings  for those
              particular characters or add new mappings (normally for composite characters).

              This is used for -Tutf8, -Thtml, and -Txhtml.

       unitwidth n
              Quantities in the font files are given in machine units for fonts whose point  size
              is n scaled points.

       unscaled_charwidths
              Make  the font handling module always return unscaled glyph widths.  Needed for the
              grohtml device.

       use_charnames_in_special
              This command indicates  that  troff  should  encode  named  glyphs  inside  special
              commands.

       vert n The vertical resolution is n machine units.

       The  res,  unitwidth, fonts, and sizes lines are compulsory.  Not all commands in the DESC
       file are used by troff itself; some of the keywords (or even additional ones) are used  by
       postprocessors to store arbitrary information about the device.

       Here  a  list  of  obsolete keywords which are recognized by groff but completely ignored:
       spare1, spare2, biggestfont.

   Font file format
       A font file has two sections; empty lines are ignored in both of them.

       The first section is a sequence of lines each containing a  sequence  of  blank  delimited
       words;  the  first  word  in the line is a key, and subsequent words give a value for that
       key.

       ligatures lig1 lig2 ... lign [0]
              Glyphs lig1, lig2, ..., lign are ligatures; possible ligatures are ff, fi, fl, ffi,
              and ffl.  For backwards compatibility, the list of ligatures may be terminated with
              a 0.  The list of ligatures may not extend over more than one line.

       name F The name of the font is F.

       slant n
              The glyphs of the font have a slant of n degrees.  (Positive means forward.)

       spacewidth n
              The normal width of a space is n.

       special
              The font is special; this means that when a glyph is requested that is not  present
              in the current font, it is searched for in any special fonts that are mounted.

       Other  commands  are ignored by troff but may be used by postprocessors to store arbitrary
       information about the font in the font file.

       The first section can contain comments which start with the # character and extend to  the
       end of a line.

       The  second section contains one or two subsections.  It must contain a charset subsection
       and it may also contain a kernpairs subsection.   These  subsections  can  appear  in  any
       order.  Each subsection starts with a word on a line by itself.

       The  word  charset  starts  the  charset  subsection.   The  charset line is followed by a
       sequence of lines.  Each line gives information for one glyph.  A line comprises a  number
       of fields separated by blanks or tabs.  The format is

              name metrics type code [entity_name] [-- comment]

       name  identifies  the  glyph: if name is a single glyph c then it corresponds to the groff
       input character c; if it is of the form  \c  where  c  is  a  single  character,  then  it
       corresponds  to  the  special  character \[c]; otherwise it corresponds to the groff input
       character \[name].  If it is exactly two characters xx it can be entered  as  \(xx.   Note
       that  single-letter special characters can't be accessed as \c; the only exception is ‘\-’
       which is identical to ‘\[-]’.  The name --- is special and indicates  that  the  glyph  is
       unnamed; such glyphs can only be used by means of the \N escape sequence in troff.

       The type field gives the glyph type:

       1      means the glyph has a descender, for example, ‘p’;

       2      means the glyph has an ascender, for example, ‘b’;

       3      means the glyph has both an ascender and a descender, for example, ‘(’.

       The  code field gives the code which the postprocessor uses to print the glyph.  The glyph
       can also be input to groff using this code by means of the \N escape sequence.   The  code
       can  be  any integer.  If it starts with a 0 it is interpreted as octal; if it starts with
       0x or 0X it is interpreted as hexadecimal.  Note, however, that  the  \N  escape  sequence
       only accepts a decimal integer.

       The  entity_name field gives an ASCII string identifying the glyph which the postprocessor
       uses to print that glyph.  This field is optional and is currently used by grops to  build
       sub-encoding  arrays for PS fonts containing more than 256 glyphs.  (It has also been used
       for grohtml's entity names but for efficiency reasons this data is now  compiled  directly
       into grohtml.)

       Anything on the line after the encoding field or ‘--’ are ignored.

       The  metrics  field  has  the  form  (in  one  line;  it  is  broken  here for the sake of
       readability):

              width[,height[,depth[,italic-correction
              [,left-italic-correction[,subscript-correction]]]]]

       There must not be any spaces between these subfields.  Missing subfields  are  assumed  to
       be  0.   The  subfields  are  all  decimal  integers.  Since there is no associated binary
       format, these values are not required to fit into a variable of type char as they  are  in
       ditroff.  The width subfields gives the width of the glyph.  The height subfield gives the
       height of the glyph (upwards is positive); if a glyph does not extend above the  baseline,
       it should be given a zero height, rather than a negative height.  The depth subfield gives
       the depth of the glyph, that is, the distance below the lowest point below the baseline to
       which  the  glyph  extends (downwards is positive); if a glyph does not extend below above
       the baseline, it should be given a zero depth, rather than a negative depth.  The  italic-
       correction subfield gives the amount of space that should be added after the glyph when it
       is immediately to be followed by a glyph from a roman  font.   The  left-italic-correction
       subfield  gives  the  amount  of  space  that  should be added before the glyph when it is
       immediately to be preceded by a glyph from a roman font.  The  subscript-correction  gives
       the  amount  of  space that should be added after a glyph before adding a subscript.  This
       should be less than the italic correction.

       A line in the charset section can also have the format

              name "

       This indicates that name is just another name for the glyph  mentioned  in  the  preceding
       line.

       The word kernpairs starts the kernpairs section.  This contains a sequence of lines of the
       form:

              c1 c2 n

       This means that when glyph c1 appears next to glyph c2 the space between  them  should  be
       increased by n.  Most entries in kernpairs section have a negative value for n.

FILES

       /usr/share/groff/1.22.3/font/devname/DESC   Device description file for device name.

       /usr/share/groff/1.22.3/font/devname/F      Font file for font F of device name.

SEE ALSO

       groff_out(5), troff(1), addftinfo(1), afmtodit(1)

       A man-page name(n) of section n can be viewed either with
              $ man n name
       for text mode or
              $ groffer nname"
       for graphical mode (default is PDF mode).

COPYING

       Copyright © 1989-2014 Free Software Foundation, Inc.

       This file is part of groff (GNU roff), which is a free software project.

       You can redistribute it and/or modify it under the terms of the GNU General Public License
       as published by the Free Software Foundation, either version 2 of the License, or (at your
       option) any later version.

       You should have received a copy of the GNU General Public License along with this program.
       If not, see GPL2 ⟨http://www.gnu.org/licenses/gpl-2.0.html⟩.