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 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  print-
       able  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  Com-
       parison 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; sym-
       bol 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  developed  by  Agfa/Compu-
       graphic.  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 rudi-
       mentary 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 differ-
       ences in glyph metrics may be particularly noticeable with composite parentheses, brackets, and braces used by eqn(1).  A
       script, located in /usr/share/groff/1.20.1/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 assign-
       ments; 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/1.20.1/font/devlj4/DESC  Device description file.

       /usr/share/groff/1.20.1/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 1.20.1                                     9 January 2009                                              LJ4_FONT(5)