This library provides for reading and writing of TeX font metric (TFM)
files.  Only a single file may be read or written at a time.

None of the code that processes the TFM commands actually explains what
the precise definition of those commands are.  For that, you should look
at the definition of the TFM format in Metafont: The Program, by Don
Knuth, chapter 46.  It is also in the TeXware program tftopl,
TeX: The Program, and other places.

The header file is ../include/tfm.h.  It explains the basics of how to
use these routines.  The source files in this directory do not repeat
that explanation.

TFM format was extended in 1990 to allow for complicated ligatures.
We do not recognize all the distinctions; all ligatures are simply
collapsed into the pre-1990 form, character A followed by character B
leads to character C.
