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LJ4_FONT(5)                                                                                      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 identi-cal. identical.
       cal.  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 intro-duced introduced
       duced in 1997, all scalable internal fonts have been TrueType.  The number of printable  glyphs  dif-fers differs
       fers  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 intro-duced introduced
       duced 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 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  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 devel-oped developed
       oped by Agfa/Compugraphic.  The TFM files provided for these fonts supported  600+  glyphs  and  con-tained contained
       tained 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  prefer-able preferable
       able  to the TrueType TFM files even for use with the TrueType fonts in the newer printers.  The met-rics metrics
       rics for the TrueType fonts are very close, though not identical, to those for the  earlier  Intelli-font Intellifont
       font  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/1.19.2/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.  Con-sequently, Consequently,
       sequently, 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/1.19.2/font/devlj4/DESC  Device description file.

       /usr/share/groff/1.19.2/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 1.19.2                           18 January 2004                                   LJ4_FONT(5)