Re: Normalisation and matching

I wrote:

> I see two advantages to this approach.  First, it allows
> presentational details to be preserved (like fullwidth characters,
> superscript characters, sharp-s, etc).

I forgot the most compelling presentational detail: mixed case.

My message focused on the issue of whether to pre-apply Nameprep.  If
we consider the similar issue of whether to pre-apply normalization
(without the rest of Nameprep), the argument against doing so becomes
even stronger.  If the receiver is going to compare the address or
convert it to ASCII, and the string did not arrive pre-folded, then
the receiver will need to apply case-folding, which is a sufficiently
heavyweight operation that there's no significant advantage in having
the string arrive pre-normalized; the receiver might as well just apply
all of Nameprep, in which case any pre-normalization is redundant.  On
the other hand, if the receiver is not going to compare the address or
convert it to ASCII, then pre-normalization wouldn't help it at all.

AMC