LJ4_FONT(5)							File Formats Manual						       LJ4_FONT(5)

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  point  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  approxi-
       mately 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(1)
       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 Refer-
       ence 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(1) 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 x 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'' x 17''), the maxi-
       mum 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'' x 11'' or A5), a greater resolution (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 kern 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/1.21/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 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/1.21/font/devlj4/DESC  Device description file.

       /usr/share/groff/1.21/font/devlj4/F     Font description file for font F.

SEE ALSO

       groff(1), groff_diff(1), hpftodit(1), grolj4(1), groff_font(5)

Groff Version 1.21						 31 December 2010						       LJ4_FONT(5)