I think that the normalization function in unicodeobject.c (only used for internal functions) can skip any character different than a-z, A-Z and 0-9. Something like:
>>> import re
>>> def normalize(name): return re.sub("[^a-z0-9]", "", name.lower())
...
>>> normalize("UTF-8")
'utf8'
>>> normalize("ISO-8859-1")
'iso88591'
>>> normalize("latin1")
'latin1'
So ISO-8859-1, ISO885-1, LATIN-1, latin1, UTF-8, utf8, etc. will be normalized to iso88591, latin1 and utf8.
I don't know any encoding name where a character outside a-z, A-Z, 0-9 means anything special. But I don't know all encoding names! :-)