.ig
Copyright (C) 1989-1995, 2001-2004, 2006-2009, 2012
  Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be included in
translations approved by the Free Software Foundation instead of in
the original English.
..
.
.do nr groff_font_C \n[.C]
.cp 0
.
.
.\" Like TP, but if specified indent is more than half
.\" the current line-length - indent, use the default indent.
.de Tp
.  ie \\n(.$=0:((0\\$1)*2u>(\\n(.lu-\\n(.iu)) .TP
.  el .TP "\\$1"
..
.
.
.TH GROFF_FONT @MAN5EXT@ "@MDATE@" "Groff Version @VERSION@"
.
.
.SH NAME
groff_font \- format of groff device and font description files
.
.
.SH DESCRIPTION
The groff font format is roughly a superset of the ditroff
font format.
.
The font files for device
.I name
are stored in a directory
.BI dev name\c
\&.
.
There are two types of file: a
device description file called
.B DESC
and for each font\~\c
.I F
a font file called\~\c
.IR F .
.
These are text files;
unlike the ditroff font format,
there is no associated binary format.
.
.
.SS DESC file format
.
The DESC file can contain the following types of line as shown below.
.
Later entries in the file override previous values.
.
.LP
Empty lines are ignored.
.
.TP
.B charset
This line and everything following in the file are ignored.
.
It is allowed for the sake of backwards compatibility.
.
.TP
.BI "family " fam
The default font family is
.IR fam .
.
.TP
.BI "fonts " "n F1 F2 F3 \|.\|.\|.\| Fn"
Fonts
.IR F1 ", \|.\|.\|., " Fn
are mounted in the font positions
.IR m "\|+\|1, \|.\|.\|., " m \|+\| n
where
.I m
is the number of styles.
.
This command may extend over more than one line.
.
A font name of\~\c
.B 0
causes no font to be mounted on the corresponding font position.
.
.TP
.BI "hor " n
The horizontal resolution is
.IR n \~\c
machine units.
.
.TP
.BI "image_generator "  string
Needed for
.B \%grohtml
only.
.
It specifies the program to generate PNG images from
PostScript input.
.
Under GNU/Linux this is usually
.I gs
but under other systems (notably cygwin) it might be set to another name.
.
.TP
.BI "paperlength " n
The physical vertical dimension of the output medium in machine units.
.
This isn't used by
.B troff
itself but by output devices.
.
Deprecated.
.
Use
.B papersize
instead.
.
.TP
.BI "papersize " string
Select a paper size.
.
Valid values for
.I string
are the ISO paper types A0\[en]A7, B0\[en]B7, C0\[en]C7, D0\[en]D7,
DL, and the US paper
types letter, legal, tabloid, ledger, statement, executive, com10, and
monarch.
.
Case is not significant for
.IR string
if it holds predefined paper types.
.
Alternatively,
.I string
can be a file name (e.g.\& `/etc/papersize'); if the file can be opened,
.B groff
reads the first line and tests for the above paper sizes.
.
Finally,
.I string
can be a custom paper size in the format
.IB length , width
(no spaces before and after the comma).
.
Both
.I length
and
.I width
must have a unit appended; valid values are `i' for inches, `c' for
centimeters, `p' for points, and `P' for picas.
.
Example:
.BR 12c,235p .
.
An argument which starts with a digit is always treated as a custom paper
format.
.
.B papersize
sets both the vertical and horizontal dimension of the output medium.
.
.IP
More than one argument can be specified;
.B groff
scans from left to right and uses the first valid paper specification.
.
.TP
.BI "paperwidth " n
The physical horizontal dimension of the output medium in machine units.
.
Deprecated.
.
Use
.B papersize
instead.
.
This isn't used by
.BR troff
itself but by output devices.
.
.TP
.B pass_filenames
Make troff tell the driver the source file name being processed.
.
This is achieved by another tcommand:
.BR F \~\c
.IR filename .
.
.TP
.BI "postpro " program
Use
.I program
as the postprocessor.
.
.TP
.BI "prepro " program
Call
.I program
as a preprocessor.
.
.TP
.BI "print "  program
Use
.I program
as the spooler program for printing.
.
If omitted, the
.B \-l
and
.B \-L
options of
.B groff
are ignored.
.
.TP
.BI "res " n
There are
.I n
machine units per inch.
.
.TP
.BI "sizes " "s1 s2 \|.\|.\|.\| sn " 0
This means that the device has fonts at
.IR s1 ,
.IR s2 ", \|.\|.\|., " sn
scaled points.
.
The list of sizes must be terminated by a
.BR 0 .
.
Each
.I si
can also be a range of sizes
.IR m \- n .
.
The list can extend over more than one line.
.
.TP
.BI "sizescale " n
The scale factor for point sizes.
.
By default this has a value of 1.
.
One
.I
scaled point
is equal to
one
.RI point\|/\| n .
.
The arguments to the
.B unitwidth
and
.B sizes
commands are given in scaled points.
.
.TP
.BI "styles " "S1 S2 \|.\|.\|.\| Sm"
The first
.I m
font positions are associated with styles
.IR S1 ", \|.\|.\|., " Sm .
.
.TP
.B tcommand
This means that the postprocessor can handle the
.B t
and\~\c
.B u
output commands.
.
.TP
.B unicode
Indicate that the output device supports the complete Unicode
repertoire.
.
Useful only for devices which produce
.I character entities
instead of glyphs.
.
.IP
If
.B unicode
is present, no
.B charset
section is required in the font description files since the Unicode
handling built into
.B groff
is used.
.
However, if there are entries in a
.B charset
section, they either override the default mappings for those
particular characters or add new mappings (normally for composite
characters).
.
.IP
This is used for
.BR \-Tutf8 ,
.BR \-Thtml ,
and
.BR \-Txhtml .
.
.TP
.BI "unitwidth " n
Quantities in the font files are given in machine units
for fonts whose point size is
.IR n \~\c
scaled points.
.
.TP
.B unscaled_charwidths
Make the font handling module always return unscaled glyph widths.
.
Needed for the
.B \%grohtml
device.
.
.TP
.B use_charnames_in_special
This command indicates that troff should encode named glyphs inside
special commands.
.
.TP
.BI "vert " n
The vertical resolution is
.IR n \~\c
machine units.
.
.LP
The
.BR res ,
.BR unitwidth ,
.BR fonts ,
and
.B sizes
lines are compulsory.
.
Not all commands in the DESC file are used by
.B troff
itself; some of the keywords (or even additional ones) are used by
postprocessors to store arbitrary information about the device.
.
.LP
Here a list of obsolete keywords which are recognized by
.B groff
but completely ignored:
.BR spare1 ,
.BR spare2 ,
.BR biggestfont .
.
.
.SS Font file format
.
A font file has two sections;
empty lines are ignored in both of them.
.
.LP
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.
.
.TP
.BI "ligatures " "lig1 lig2 \|.\|.\|.\| lign \fR[" 0 \fR]
Glyphs
.IR lig1 ,
.IR lig2 ", \|.\|.\|., " lign
are ligatures; possible ligatures are
.BR ff ,
.BR fi ,
.BR fl ,
.BR ffi ,
and
.BR ffl .
.
For backwards compatibility, the list of ligatures may be terminated
with a\~\c
.BR 0 .
.
The list of ligatures may not extend over more than one line.
.
.TP
.BI "name " F
The name of the font is\~\c
.IR F .
.
.TP
.BI "slant " n
The glyphs of the font have a slant of
.IR n \~\c
degrees.
.
(Positive means forward.)
.
.TP
.BI "spacewidth "  n
The normal width of a space is\~\c
.IR n .
.
.TP
.B special
The font is
.IR 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.
.
.LP
Other commands are ignored by
.B troff
but may be used by postprocessors to store arbitrary information
about the font in the font file.
.
.LP
The first section can contain comments which start with the
.B #
character and extend to the end of a line.
.
.LP
The second section contains one or two subsections.
.
It must contain a
.I charset
subsection
and it may also contain a
.I kernpairs
subsection.
.
These subsections can appear in any order.
.
Each subsection starts with a word on a line by itself.
.
.LP
The word
.B charset
starts the charset subsection.
.
The
.B 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
.
.IP
.I name metrics type code
.RI [ entity_name ]
.RB [ \-\-
.IR comment ]
.
.LP
.I name
identifies the glyph:
if
.I name
is a single glyph
.I c
then it corresponds to the groff input character
.IR c ;
if it is of the form
.BI \[rs] c
where c is a single character, then it
corresponds to the special character
.BI \[rs][ c ]\fR;
otherwise it corresponds to the groff input character
.BI \[rs][ name ]\fR.
.
If it is exactly two characters
.I xx
it can be entered as
.BI \[rs]( xx\fR.
.
Note that single-letter special characters can't be accessed as
.BI \[rs] c\fR;
the only exception is `\[rs]\-' which is identical to `\[rs][\-]'.
.
The name
.B \-\-\-
is special and indicates that the glyph is unnamed;
such glyphs can only be used by means of the
.B \[rs]N
escape sequence in
.BR troff .
.
.LP
The
.I type
field gives the glyph type:
.
.TP
1
means the glyph has a descender, for example, `p';
.
.TP
2
means the glyph has an ascender, for example, `b';
.
.TP
3
means the glyph has both an ascender and a descender, for example,
`('.
.
.LP
The
.I 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
.B \[rs]N
escape sequence.
.
The code can be any integer.
.
If it starts with a\~\c
.B 0
it is interpreted as octal;
if it starts with
.B 0x
or
.B 0X
it is interpreted as hexadecimal.
.
Note, however, that the
.B \[rs]N
escape sequence only accepts a decimal integer.
.
.LP
The
.I 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
.B grops
to build sub-encoding arrays for PS fonts containing more than 256 glyphs.
.
(It has also been used for
.BR \%grohtml 's
entity names but for efficiency reasons this data is now compiled directly
into
.BR \%grohtml .)
.
.LP
Anything on the line after the encoding field or `\-\-' are ignored.
.
.LP
The
.I metrics
field has the form (in one line; it is broken here for the sake of
readability):
.
.IP
.I width\c
.RI [\fB, height\c
.RI [\fB, depth\c
.RI [\fB, italic-correction
.br
.RI [\fB, left-italic-correction\c
.RI [\fB, subscript-correction ]]]]]
.
.LP
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
.B char
as they are in ditroff.
.
The
.I width
subfields gives the width of the glyph.
.
The
.I 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
.I 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
.I 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
.I 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
.I 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.
.
.LP
A line in the charset section can also have the format
.
.IP
.I
name \fB"
.
.LP
This indicates that
.I name
is just another name for the glyph mentioned in the
preceding line.
.
.LP
The word
.B kernpairs
starts the kernpairs section.
.
This contains a sequence of lines of the form:
.
.IP
.I c1 c2 n
.
.LP
This means that when glyph
.I c1
appears next to glyph
.I c2
the space between them should be increased by\~\c
.IR n .
.
Most entries in kernpairs section have a negative value for\~\c
.IR n .
.
.
.SH FILES
.
.Tp \w'@FONTDIR@/devname/DESC'u+3n
.BI @FONTDIR@/dev name /DESC
Device description file for device
.IR name .
.
.TP
.BI @FONTDIR@/dev name / F
Font file for font\~\c
.I F
of device
.IR name .
.
.
.SH "SEE ALSO"
.
.BR groff_out (@MAN5EXT@),
.BR @g@troff (@MAN1EXT@).
.
.cp \n[groff_font_C]
.
.\" Local Variables:
.\" mode: nroff
.\" End: