Comments on the Unicode Codepoints and IDNA Internet-Draft

[Stephane Bortzmeyer]

On Thu, Jul 31, 2008 at 08:12:51AM +0800,
 mail at edmon <mail at edmon.info> wrote 
 a message of 234 lines which said:

> toNFKC(toCaseFolded(toNFKC(label))) != label

This is interesting but it completely changes the tables, which are
currently per character, not per label. This would imply to change the
other rules (for instance, from "cp is not in Exceptions" to "no cp in
the label is in Exceptions").

With the current tables, checking if a label is legal is almost
trivial (only composed of legal characters, with the special annoying
rule of context-allowed characters). With your proposal, checking if a
label is legal means running Unicode routines such as NFKC.