Re: hidden composites

["Berthold K.P. Horn" <bkph@ai.mit.edu>]

   I wrote (thinking about extracting information from PFA/PFB files):

   Also, since Berthold brings up PFMs, I've been told for a long time that
   PFMs have almost all the information you'll find in an AFM but some
   things are missing, but never known exactly what (if I had to guess I'd
   probably go for the composite character entries).  I'd be really interested
   if someone who knows could enlighten me, just for curiosity's sake.

PFM's are rather anaemic.  They do not contain character bounding boxes.
They contain no information on unencoded characters.  They do not have
the font encoding.  Some of these flaws are shared with TFM files.

   (Similarly, I've never really understood why Adobe introduced PFMs and
   MMM files when they had AFMs and AMFMs, it just seems to add needless
   complexity and incompatibility to font issues.)

For the same reason TeX uses TFM's rather than say PL's: speed and
compactness.  For many fonts the AFM file is almost as large as the
actual font itself in PFB format and takes a long time to parse.  
I don't know what platform you are on, but if you are on a Mac then you
have another weirdness, which is the `screen font' suitcase the only real 
use of which is the FOND resource that contains the font's metrics - 
quite like the PFM file.

As for AMFM's, I have never seen one and am beginning to doubt whether
they really exist.  I always make AFM or TFM files for my Multiple
Master instances directly from the installed font.

Berthold