Re: Canonical Combining Classes

From: John Hudson (
Date: Thu Jan 13 2000 - 16:24:05 EST

At 06:45 PM 12-01-00 -0800, Kenneth Whistler wrote:

>These are all "fixed position classes". The intent on these was to
>indicate combining marks that always come in some defined position,
>and don't interact and combine in stacks. A major change between
>Unicode 2.0 and Unicode 3.0 was to bleed off many of the fixed position
>classes into combining class 0 where there really was no interaction
>between them; only a relatively small handful of the fixed position
>classes were retained -- with the numbers unchanged insofar as possible.

>This change simplified a number of things for normalization and was done
>because there didn't seem to be any strong reason to keep all the
>fixed position class assignments. They made no real difference for

Thanks for this information, Ken. Am I right in thinking, though, that the
classes I listed have not been bled off into combining class 0 in Unicode
3.0, since they are still listed in the current UnicodeData.txt file?

I'm building some developer materials for type designers and font
developers, and I want to be able to present as much of the Unicode
character data as possible in immediately understandable terms. That is,
I'm expanding the abbreviations and tags in the UnicodeData.txt files into
simple definitions that will, in turn, be expanded into brief explanations.
So it would be nice to have something other than this list of numbers for
the 'fixed position class' entries in this field. Is there a list I can
refer to somewhere?

John Hudson

Tiro Typeworks
Vancouver, BC

This archive was generated by hypermail 2.1.2 : Tue Jul 10 2001 - 17:20:58 EDT