>>>>> "Lars" == Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

 Lars> Ok, if one runs in unibyte mode, and there are characters that
 Lars> are not in the \000-\177 range, then the characters must be the
 Lars> result of current-language-environment.

I don't think there's anything to stop you typing ça in an `English'
current-language-environment which claims only to know about `ascii'.

 Lars> How does one go from current-language-environment to a charset?

I don't think you do.  I think the unibytten need a default non-ASCII
Emacs charset, related to (instead of?) the MIME one.  That's what I
did with TM for MBSK Emacs (though I may have confused the two sorts
of charsets).  Perhaps it could be defvar'ed from `charset' in
`language-info-alist' if `unibyte-display' is defined?  (Not that I
claim to understand this stuff.)

Hurrah for sanctioning of unibyte!