My facts below are a bit fuzzym because I don't have reference materials
available where I am writing.
The modern Cheyenne materials I've seen seem - mostly prepared by or with
advice from Wayne Leman - to use pretty much the standard symbol ASCII set,
with capitalization or under dots to indicate voiceless vowels. I believe
the latter are predictable if you know the rule, but the rule is somewhat
complex. I can't recall if it is considered necessary to mark (pitch)
accents. I can dig up and xerox an orthography key for you if you wish.
In general, "Plains" Algonquian languages (not a genetic subgroup of
Algonquian) can be handled if you have a font with a symbol set that
includes theta, glottal stop, and aesc (ae) and/or open o (backward c), plus
acute accented vowels, unless voiceless vowels are marked explicitly. The
extra vowel symbols (aesc and open o) are needed because Algonquian
languages tend to have four and six vowel systems that don't work well with
the standard Roman five vowel symbols (some of the PA vowels are more or
less centered on the cracks between the ranges the standard symbols cover).
Caddoan languages can manage with just the additional glottal stop and
acute-accented vowels, I think.
Siouan languages are a bit more complex, requiring certain nasal vowels,
marked with a nasal hook diacritic or a following raised n or eta, gamma,
glottal stop, and sometimes things like edh, theta, eng, or symbols for
pharyngeal fricatives for particular language.
Kiowa is the worst case Plains language I've found so far, mainly because it
has three different pitch contours plus nasalization that can cooccur on each
of the vowels, and there is a sixth vowel (open o, I believe).
I am assuming in all cases above that aspiration and ejection are written
with the aid of in-line h and glottal stop. If not, add a raised h and
glottal stop symbol.
John Koontz (koontz@bldr.nist.gov)