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	 scal-
       able  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 dif-
       fers slightly between Intellifont and TrueType  fonts  (generally,  the
       TrueType	 fonts	include more glyphs), and there are some minor differ-
       ences 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(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 Reference Man-
       ual.

       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  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'' 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 Laser-
       Jet 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	Laser-
       Jet 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 informa-
       tion, 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  accept-
       able,  a	 few glyphs may fail to print as expected.  The differences in
       glyph metrics may be particularly noticeable with  composite  parenthe-
       ses,  brackets,	and  braces  used  by  eqn(1).	 A  script, located in
       /usr/share/groff/1.22.2/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.  Con-
       sequently, 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/1.22.2/font/devlj4/DESC
	      Device description file.

       /usr/share/groff/1.22.2/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 1.22.2		7 February 2013			   LJ4_FONT(5)