GROFF_FONT(5)
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. Unlike the ditroff font format, there is no
associated binary 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; there
is no associated binary format.
DESC file format
The DESC file can contain the following types of line:
res n There are n machine units per inch.
hor n The horizontal resolution is n machine units.
vert n The vertical resolution is n machine units.
sizescale n
The scale factor for pointsizes. 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.
unitwidth n
Quantities in the font files are given in machine
units for fonts whose point size is n scaled
points.
tcommand
This means that the postprocessor can handle the t
and u output commands.
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 m-n. The list can extend over more than one
line.
styles S1 S2...Sm
The first m font positions will be associated with
styles S1...Sm.
fonts n F1 F2 F3...Fn
Fonts F1...Fn will be 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 will cause no font to be mounted on the
corresponding font position.
family fam
The default font family is fam.
charset
This line and everything following in the file are
ignored. It is allowed for the sake of backwards
compatibility.
The res, unitwidth, fonts and sizes lines are compulsory.
Other commands are ignored by troff but may be used by
postprocessors to store arbitrary information about the
device in the DESC file.
Font file format
A font file has two sections. 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.
name F The name of the font is F.
spacewidth n
The normal width of a space is n.
slant n
The characters of the font have a slant of n
degrees. (Positive means forward.)
ligatures lig1 lig2...lign [0]
Characters lig1, lig2,...,lign are ligatures; pos-
sible ligatures are ff, fi, fl and ffl. For back-
wards compatibility, the list of ligatures may be
terminated with a 0. The list of ligatures may not
extend over more than one line.
special
The font is special; this means that when a charac-
ter is requested that is not present in the current
font, it will be 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 character. A line com-
prises a number of fields separated by blanks or tabs. The
format is
name metrics type code comment
name identifies the character: if name is a single charac-
ter 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 groff input character \c; oth-
erwise it corresponds to the groff input character \[name]
(if it is exactly two characters xx it can be entered as
\(xx.) Groff supports eight bit characters; however some
utilities has difficulties with eight bit characters. For
this reason, there is a convention that the name charn is
equivalent to the single character whose code is n . For
example, char163 would be equivalent to the character with
code 163 which is the pounds sterling sign in ISO Latin-1.
The name --- is special and indicates that the character
is unnamed; such characters can only be used by means of
the \N escape sequence in troff.
The type field gives the character type:
1 means the character has an descender, for example,
p;
2 means the character has an ascender, for example,
b;
3 means the character has both an ascender and a
descender, for example, (.
The code field gives the code which the postprocessor uses
to print the character. The character 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 will be interpreted as octal; if it starts with 0x
or 0X it will be intepreted as hexadecimal.
Anything on the line after the code field will be ignored.
The metrics field has the form:
width[,height[,depth[,italic_correc-
tion[,left_italic_correction[,subscript_correc-
tion]]]]]
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 character. The height
subfield gives the height of the character (upwards is
positive); if a character does not extend above the base-
line, it should be given a zero height, rather than a neg-
ative height. The depth subfield gives the depth of the
character, that is, the distance below the lowest point
below the baseline to which the character extends (down-
wards is positive); if a character does not extend below
above the baseline, it should be given a zero depth,
rather than a negative depth. The italic_correction sub-
field gives the amount of space that should be added after
the character when it is immediately to be followed by a
character from a roman font. The left_italic_correction
subfield gives the amount of space that should be added
before the character when it is immediately to be preceded
by a character from a roman font. The subscript_correc-
tion gives the amount of space that should be added after
a character 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
character 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 character c1 appears next to charac-
ter c2 the space between them should be increased by n.
Most entries in kernpairs section will have a negative
value for n.
FILES
/usr/lib/groff/font/devname/DESC
Device description file for device name.
/usr/lib/groff/font/devname/F
Font file for font F of device name.
SEE ALSO
groff_out(5) troff(1).