groff_font(5) — Linux manual page

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groff_font(5)                File Formats Manual               groff_font(5)

Name         top

       groff_font - format of groff device and font description files

Description         top

       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.

              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.

              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, ...,

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

              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.

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

              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

       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.

              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 (on one line; it may be broken here
       for the sake of readability):


       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 baseline to
       which the glyph extends (downwards is positive); if a glyph does not
       extend below 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         top

              Device description file for device name.

              Font file for font F of device name.

See Also         top

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

COLOPHON         top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, see ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-07-14.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-07-12.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

groff            16 May 2020                   groff_font(5)

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