> One that occurs to me might be the Khoisan languages of Africa, > which I believe commonly use "!" (U+0021) for a click sound. > This is almost exactly the same problem you are describing for Tongva.
U+01C3 LATIN LETTER RETROFLEX CLICK (General Category Lo) was encoded precisely for this. It is to be *distinguished* from U+0021 '!' EXCLAMATION MARK to avoid all of the processing problems which would attend having a punctuation mark as part of your letter orthography. A Khoisan orthography keyboard should distinguish the two characters (if, indeed, it makes any use at all of the exclamation mark per se), so that users can tell them apart and enter them correctly. --Ken
