Michael, you've seen what they are using. How will the community be served when type designers start creating fonts that have a cap-height glyph for 0294 supplemented by a modified capital P?
The characters can be seen on the web at http://www.wkss.nt.ca/HTML/08_ProjectsReports/PDF/DogribPlaceCaribouHabitat2002.pdf
Search on "Small Clear Lake" in the file on "Jackfish" and "Moosenose" and "glottal stop" for a few of many examples.
These characters are obviously being used.
See also http://members.tripod.com/~DeneFont/win_char.htm
There appears to me to be two possibilities for Unicode:
1. Encode a new character for the lowercase glottal stop and recategorize U+2094 as uppercase.
2. Encode two new characters and leave U+2094 as is.
The second suggestion has the advantage that a font designer would be more free than otherwise to render the uppercase glottal stop to match more closely other uppercase characters in a particular lettering style.
Jim Allan

