[idn] cc

[Frank Ernens <fgernens@enternet.com.au>]

Harald wrote

> Specifying that compatibility characters MUST NOT be sent on the wire when 
> supporting the "internationalized domain name" service, together with a 
> recommendation that a client SHOULD fold compatibility characters presented 
> to it at the application user interface is a self-consistent position.

Yes, but I think it should be "a client MAY fold compatibility
characters" rather than "a client SHOULD".

The reason is that both folding and not folding produce nasty
surprises for some characters and some people. I see it as a
user preference setting in a client application, with a factory
set default appropriate for most users of that client. A novice
user using a system which still allows compatibility characters
in keyboard input would be best off with folding; while an expert
on a pure Unicode system is almost certainly better off without
folding (except maybe for "_" and "~" were they to be allowed).
A very capable client could even allow the user to tailor folding
based on information in the unidata file, but most Unicode
implementations don't give the application programmer that much
control.