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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  avail‐
       able  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 True‐
       Type.  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 re‐
       maining scalable fonts, as well as the Lineprinter font, support numerous symbol sets, suffi‐
       cient 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 resolu‐
       tion of 7200 units per inch, they use a 16-bit signed integer for cursor positioning; if  de‐‐
       vlj4  is  to support U.S. ledger paper (11 in × 17 in; in = inch), the maximum usable resolu‐
       tion 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 gen‐
       erally 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 in‐
       troduced, 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 infor‐
       mation; 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 print‐
       ers.   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 ex‐
       pected.  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  spe‐
       cial 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 avail‐
       able.  Consequently, many glyphs lacking assigned code points were assigned by HP to the Pri‐
       vate 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)



groff 1.22.4                                23 March 2022                                LJ4_FONT(5)