[XeTeX] accessing fonts from TeX tree and glyphs without Unicode slot

[Adam Twardoch]

Arthur Reutenauer wrote:
> By the way, do you know of any standardization that has been made for
> PUA codepoints? 
I will reply here but I don't think the list will be interested in 
continuing to hear this discussion.

"Standardized private codepoints" has as much sense as "controlled 
freedom." The whole purpose of the Private Use Area is that it is 
non-standardized.
> I noticed, for example, that FontForge shows many of the
> code points as being represented by particular glyphs (in the title
> area of the character, like it does for non-private code points; for
> example, the glyph for U+0041 is shown with an 'A' in the title area,
> etc.); arabic glyphs, starting from U+E600, or devanagari, starting from
> U+E900. 
Some companies and user groups have adapted their own internal 
conventions as for how to assign some PUA codepoints consistently across 
the fonts they create or in some limited-use applications (such as 
linguistic transcriptions of historical documents of a certain kind). 
But the whole idea of PUA is that the same codepoint space is occupied 
by different glyphs depending on which vendor has created the font or 
which organization/user group has created a convention. Examples: SIL 
assigns the PUA codepoint U+F1A1 to "MODIFIER LETTER SMALL AE" while 
MUFI assigns it to "LATIN ABBREVIATION SIGN SMALL CON"; Apple assigns 
the PUA codepoint U+F73F to "NSPrevFunctionKey" while Adobe assigns it 
to "questionsmall"; CSUR assigns the PUA codepoint U+F8FF to "KLINGON 
MUMMIFICATION GLYPH" while Apple assigns it to "APPLE LOGO". In early 
versions of Windows, Microsoft used PUA for some Hebrew, Arabic and Thai 
presentational forms and it's possible that FontForge is using these.

I have described some fundamental problems in using PUA to express 
linguistic characters at:
http://groups.msn.com/FontLab/announcements.msnw?action=get_message&mview=0&ID_Message=5794

Some further links:
http://www.unicode.org/faq/casemap_charprop.html#8
http://partners.adobe.com/public/developer/opentype/index_glyph.html#4
http://scripts.sil.org/PUA_home
http://www.opengroup.or.jp/jvc/cde/ucs-conv-e.html
http://en.wikipedia.org/wiki/Mapping_of_Unicode_characters#Private_Use_Area
http://www.evertype.com/standards/csur/
http://www.mufi.info/

Regards,
Adam

-- 

Adam Twardoch
http://www.twardoch.com/

When J. Robert Oppenheimer said "I am become death, the destroyer 
of worlds", he was not referring to the atomic bomb. He was 
referring to the Chuck Norris halloween costume he was wearing.