This WG only specifies requirements for the protocol,
so we should not focus on what registrars are/aren't
permitted to do.
Quite right. Still, is it a *requirement* that IDN not allow punctuation
and symbols other than ones that would clearly confuse users (such as
things that look like ASCII periods and things that look like ASCII hyphens)?
How about:
IDN need only support DNS names that consist of characters normally used in
words and names. These characters MAY include punctutation and symbols. IDN
names MUST NOT control characters. The IDN protocol MUST specify which
characters within any allowed charsets are not allowed in IDN names.
--Paul Hoffman, Director
--Internet Mail Consortium