Provided by: groff_1.22.4-8build1_amd64 
NAME
lj4_font - groff fonts for use with devlj4
DESCRIPTION
Nominally, all Hewlett-Packard LaserJet 4-series and newer printers have the same internal fonts: 45
scalable fonts and one bitmapped Lineprinter font. The scalable fonts are available in sizes between
0.25 points and 999.75 points, in 0.25-point increments; the Lineprinter font is available only in
8.5-point size.
The LaserJet font files included with groff assume that all printers since the LaserJet 4 are identical.
There are some differences between fonts in the earlier and more recent printers, however. The
LaserJet 4 printer used Agfa Intellifont technology for 35 of the internal scalable fonts; the remaining
10 scalable fonts were TrueType. Beginning with the LaserJet 4000-series printers introduced in 1997,
all scalable internal fonts have been TrueType. The number of printable glyphs differs slightly between
Intellifont and TrueType fonts (generally, the TrueType fonts include more glyphs), and there are some
minor differences in glyph metrics. Differences among printer models are described in the PCL 5
Comparison Guide and the PCL 5 Comparison Guide Addendum (for printers introduced since approximately
2001).
LaserJet printers reference a glyph by a combination of a 256-glyph symbol set and an index within that
symbol set. Many glyphs appear in more than one symbol set; all combinations of symbol set and index
that reference the same glyph are equivalent. For each glyph, hpftodit(1) searches a list of symbol
sets, and selects the first set that contains the glyph. The printing code generated by hpftodit is an
integer that encodes a numerical value for the symbol set in the high byte(s), and the index in the low
byte. See groff_font(5) for a complete description of the font file format; symbol sets are described in
greater detail in the PCL 5 Printer Language Technical Reference Manual.
Two of the scalable fonts, Symbol and Wingdings, are bound to 256-glyph symbol sets; the remaining
scalable fonts, as well as the Lineprinter font, support numerous symbol sets, sufficient to enable
printing of more than 600 glyphs.
The metrics generated by hpftodit assume that the DESC file contains values of 1200 for res and 6350 for
unitwidth, or any combination (e.g., 2400 and 3175) for which res × unitwidth = 7620000. Although HP
PCL 5 LaserJet printers support an internal resolution of 7200 units per inch, they use a 16-bit signed
integer for cursor positioning; if devlj4 is to support U.S. ledger paper (11 in × 17 in; in = inch), the
maximum usable resolution is 32767 ÷ 17, or 1927 units per inch, which rounds down to 1200 units per
inch. If the largest required paper size is less (e.g., 8.5 in × 11 in, or A5), a greater res (and
lesser unitwidth) can be specified.
LIMITATIONS
Font metrics for Intellifont fonts were provided by Tagged Font Metric (TFM) files originally developed
by Agfa/Compugraphic. The TFM files provided for these fonts supported 600+ glyphs and contained
extensive lists of kerning pairs.
To accommodate developers who had become accustomed to TFM files, HP also provided TFM files for the 10
TrueType fonts included in the LaserJet 4. The TFM files for TrueType fonts generally included less
information than the Intellifont TFMs, supporting fewer glyphs, and in most cases, providing no kerning
information. By the time the LaserJet 4000 printer was introduced, most developers had migrated to other
means of obtaining font metrics, and support for new TFM files was very limited. The TFM files provided
for the TrueType fonts in the LaserJet 4000 support only the Latin 2 (ISO 8859-2) symbol set, and include
no kerning information; consequently, they are of little value for any but the most rudimentary
documents.
Because the Intellifont TFM files contain considerably more information, they generally are preferable to
the TrueType TFM files even for use with the TrueType fonts in the newer printers. The metrics for the
TrueType fonts are very close, though not identical, to those for the earlier Intellifont fonts of the
same names. Although most output using the Intellifont metrics with the newer printers is quite
acceptable, a few glyphs may fail to print as expected. The differences in glyph metrics may be
particularly noticeable with composite parentheses, brackets, and braces used by eqn(1). A script,
located in /usr/share/groff/1.22.4/font/devlj4/generate, can be used to adjust the metrics for these
glyphs in the special font “S” for use with printers that have all TrueType fonts.
At the time HP last supported TFM files, only version 1.0 of the Unicode standard was available.
Consequently, many glyphs lacking assigned code points were assigned by HP to the Private Use Area (PUA).
Later versions of the Unicode standard included code points outside the PUA for many of these glyphs.
The HP-supplied TrueType TFM files use the PUA assignments; TFM files generated from more recent TrueType
font files require the later Unicode values to access the same glyphs. Consequently, two different
mapping files may be required: one for the HP-supplied TFM files, and one for more recent TFM files.
FILES
/usr/share/groff/1.22.4/font/devlj4/DESC
device description file
/usr/share/groff/1.22.4/font/devlj4/F
font description file for font F
/usr/share/groff/1.22.4/font/devlj4/generate
corrects Intellifont-based height metrics for several glyphs in the special font for TrueType CG
Times (LaserJet 4000 and later).
SEE ALSO
groff(1), hpftodit(1), grolj4(1), groff_font(5)