[XeTeX] Character alternatives

William F. Adams wadams at atlis.com
Tue Sep 14 15:28:32 CEST 2004

This is a thing which I've been trying to tackle w/ my Zapfino font 
setup (using Omega).

Unfortunately, I've gotten bollixed by otp2ocp crashing after my .otp 
pashes a certain size --- the thing which may be of interest here is 
that I hacked up a 16-bit encoding scheme for describing arbitrary 
ligatures or alternates (sans accents, sorry) with up to 32 variations 
per character. The preprint is online on the TUG2003 area at 
www.tug.org --- you maybe can get something of a sense for how I'm 
trying to make it work by looking at the OTP, it's at:

> http://members.aol.com/willadams/fonts/tex/zapfino/lat2zapf.otp

Essentially one divides the 16 bits into a six bit and two five bit 
chunks. The first six-bit is sufficient to encode all letters (cap and 
lowercase) and numbers 0--9, and have a bit or two left over for 
``swashness'' &c. and the remaining pairs of five bits would get one 
either a variant setting and succeeding lowercase, or two succeeding 
lowercase. I did up a set of Excel spreadsheets to show what these were 
while I was working on it.

The idea was that one would set up the TeX end of things to always 
access things using the above numbers, and set up a virtual font to 
access the characters in the real font---that way if a font were 
upgraded and new characters added, one would ``merely'' need to update 
the virtual font w/ the new mappings, but the .tex source could be left 


William Adams, publishing specialist
voice - 717-731-6707 | Fax - 717-731-6708

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