Posted by Thomas Phinney
I’m cross-posting this with the OpenType mailing list to try to get a wider cross-section of views.
As has been mentioned here and elsewhere, in new fonts Adobe is moving away from using Unicode Private Use Area (PUA) encodings for glyphs that are alternates or variants of another glyph that is encoded as the default form for a character. About the only thing we’d use PUA for in new fonts would be ornaments or dingbats that really don’t have their own codepoints.
We’re working on a general tune-up of our whole type library, and one of the questions which arose is, should we make such a change in revising already shipping fonts?
All of us who have discussed it at length (David Lemon, Christopher Slye and I) are quite ambivalent about this. As of our last poll I think David and I were leaning mildly against, and Christopher was mildly in favor.
Why are we angst-ridden on the topic?
Well, the reason to do it is to set an example, and to "put our money where our mouth is." We’ve been saying for several years at least that if we had it to do over again, we would not encode anything in PUA except for dingbats and the like. If we change it even in already shipping fonts, we’re sending a strong signal to other font developers, and not doing it kind of undermines the message that it’s a bad idea.
But if make this change, we’re trashing backwards compatibility for any people who have made documents in, say, Word for Windows, and used the Windows Character Map to get at some special alternate they couldn’t access directly (oldstyle figures? some neat ornament? a swash cap? I dunno). We really don’t think there are a lot of these people, but for them to get notdefs instead of their desired glyphs if they open an old doc with a newer version of the font… well, that’s pretty ugly.
Anyway, comments are welcome.