Provided by: groff_1.21-6_i386 bug

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  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 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)