Re: regex and case-fold-search problem

[Richard Stallman]

    > What about for Latin-2 characters?  Will those regexp ranges
    > change their meaning in emacs-unicode?

    Yes.  Latin-2 characters have different order in Unicode than in
    8859-2.  Those characters which are common to Latin-2 and Latin-1 are
    in the same order, but those which aren't have different places.  The
    same goes for all the other Latin-N characters where N != 1.

This suggests that perhaps there is no need to be careful about
case-folding of ranges outside of ASCII and Latin-1.

    We could have some code to map a range specified by a Lisp program
    into a range of internal character codepoints (in Unicode Emacs, the
    latter would be Unicode codepoints).  We could make this code depend
    on some user variable that states the external ordering meant by the
    application.  For example, Cyrillic users could tell Emacs that [A-Z]
    was intended to work as in KOI8-R or as in 8859-5.

This is a coherent idea, but since it is a substantial amount of work,
the question is whether it is better to do this or do nothing about
those cases.  I wonder how many programs use ranges of Latin-2 or
KOI8-R and depend on case-folding to work precisely.  Probably few or
none.