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LJ4_FONT(5)							   LJ4_FONT(5)

       lj4_font	- groff	fonts for use with devlj4

       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-

       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.

       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_font/devlj4/generate, can be used to adjust  the  met-
       rics  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.

       /usr/share/groff_font/devlj4/DESC  Device description file.

       /usr/share/groff_font/devlj4/F	  Font description file	for font F.

       groff(1), groff_diff(1),	hpftodit(1), grolj4(1),	groff_font(5)

Groff Version 1.19.2		 27 June 2014			   LJ4_FONT(5)


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