Re: [idn] WG last call documents

["Eric A. Hall" <ehall@ehsco.com>]

"Eric A. Hall" wrote:

> > I think the intended title of this document is "Stringprep Profile
> > for Internationalized Domain Names".
> 
> Based on a cursory analysis, this document is suitable as a standalone
> description of i18n domain names

Looking at this in more detail, I take that back. The i18n "domain name"
specification needs to allow any valid UCS character code, and must not be
restricted to hostname characters. As has been discussed multiple times,
there are some domain names which are not hostnames, and this model will
likely be valid in the future as well.

The obvious example of this is mailbox names. Some future version of an
email specification may allow (for example) the use of non-combining
characters in mailbox names. However, mailbox names are often stored in
DNS labels, and under the current arrangement, those mailbox names would
be normalized and lowercased as part of this process. In essence, the
rules which are currently provided impose restrictions on any future
mailbox name designs which the representative working group may come up
with in the future.

That is the obvious example. There are less-obvious examples of the same
concern. However, in general, there should be a different stringprep
profile for i18n "domain names" than for "host names", and IDNA (among
other encoding or tagging sequences) must allow for all of these
variations, rather than imposing artificial restrictions in this area.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/