(tds.info)Font bitmaps

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3.2.1 Font bitmaps
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Font bitmap files require two characteristics in addition to the above
to be uniquely identifiable: (1) the type of device (i.e., mode) for
which the font was created; (2) the resolution of the bitmap.

   Following common practice, the TDS segregates fonts with different
device types into separate directories.  See `modes.mf' in
Appendix Note: Related references for recommended mode names.

   Some printers operate at more than one resolution (e.g., at 300dpi
and 600dpi), but each such resolution will necessarily have a different
mode name. Nothing further is needed, since implicit in the TeX system
is the assumption of a single target resolution.

   Two naming strategies are commonly used to identify the resolution of
bitmap font files.  On systems that allow long filenames (and in the
original Metafont program itself), the resolution is included in the
filename (e.g., `cmr10.300pk').  On systems which do not support long
filenames, fonts are generally segregated into directories by
resolution (e.g., `dpi300/cmr10.pk').

   Because the TDS cannot require long filenames, we must use the
latter scheme for naming fonts. So we have two more subdirectory levels
under `pk' and `gf':

     texmf/fonts/pk/MODE/SUPPLIER/TYPEFACE/dpiNNN/
     texmf/fonts/gf/MODE/SUPPLIER/TYPEFACE/dpiNNN/

   * `MODE' is a name which identifies the device type (examples: `cx',
     `ljfour', `modeless').  Usually, this is the name of the Metafont
     mode used to build the PK file.  For fonts rendered as bitmaps by
     a program that does not distinguish between different output
     devices, the `MODE' name shall be simply `modeless'.  The `MODE'
     level shall not be omitted, even if only a single mode happens to
     be in use.

   * `dpiNNN' specifies the resolution of the font (examples: `dpi300',
     `dpi329').  `dpi' stands for dots per inch, i.e., pixels per inch.
     We recognize that pixels per millimeter is used in many parts of
     the world, but dpi is too traditional in the TeX world to consider
     changing now.

     The integer `NNN' is to be calculated as if using Metafont
     arithmetic and then rounded; i.e., it is the integer Metafont uses
     in its output `gf' filename.  We recognize small differences in the
     resolution are a common cause of frustration among users, however,
     and recommend implementors follow the level 0 DVI driver standard
     (see Appendix Note: Related references) in bitmap font searches
     by allowing a fuzz of +-0.2% (with a minimum of 1) in the `DPI'.


   Implementations may provide extensions to the basic naming scheme,
such as long filenames (as in the original Metafont) and font library
files (as in emTeX's `.fli' files), provided that the basic scheme is
also supported.