I hope Apple re-thinks this, because it makes PUA useless in plain text.
Doing font substitution on PUA code points was causing problems, because we have found a lot of fonts have garbage entries in their cmaps in the PUA, due to the implementation details of certain font-editing applications (which use the PUA part of the cmap as a "scratch" area). The system was basically picking a random font in many cases. Rather than have a font substitution mechanism that picks a random font, we disabled font substitution for PUA characters.
I agree this causes problems for things like file names in the Finder, but I worry whether that is an appropriate use of PUA characters. When Cuneiform is encoded, all these file names will have to be reentered.
Deborah Goldsmith Manager, Fonts / Unicode liaison Apple Computer, Inc. [EMAIL PROTECTED]
