I suggest ignoring UTR 21. Just downcase according to the 'default'
(non-normative) in the main property table for Unicode 3.0.
UTR21 equivalences too much, I think. Using UTR21 AND at the same
time consider compatibility variants to be different, would be
totally strange, I find. In addition UTR 21 results in something
that might NOT be in normal form (i.e. neither D, C, KD, or KC).
So if one uses UTR 21 caselessness, normalisation must be done
AFTER that. Plain downcasing does not result in such problems.
(Though plain uppercasing does...)
Correction: Normalisation has to be done (in principle) AFTER
a case change of any form,
otherwise the result migth not be in any one of
the defined normal forms. (I can supply
a detailed argument if you
like.)
That means for Dan's and Paul's drafts:
a)
Downcase (still preferably just that, no UTR 21); THEN normalise
(still to form KC
preferably!!!).
b) If
you want to store a *cased* original, you need not normalise that at all, or
at
most to form C, since if one want to preserve
case, one might likely want to preserve
compatibility forms as
well (even if they still should *compare* equal, even
caseless).
Sorry,
Kind regards
/kent k