> isMark '\768'
True

> isAlphaNum '\768'
True

> (isAlpha '\768', isNumber '\768')
(False,False)

This behavior comes from this piece in WCsubst.c:

unipred(u_iswalnum,(GENCAT_LT|GENCAT_LU|GENCAT_LL|GENCAT_LM|GENCAT_LO|
		    GENCAT_MC|GENCAT_ME|GENCAT_MN|
		    GENCAT_NO|GENCAT_ND|GENCAT_NL))

I'm not sure what should be done here. Is it a bug with isAlpaNum? Or with isAlpha? How does it correspond to iswalnum's behavior in C++?

(And if it's a feature and not a bug, then it should definitely be documented.)