Re: [idn] I-D ACTION:draft-ietf-idn-idna-08.txt

["Adam M. Costello" <idn.amc+0@nicemice.net.RemoveThisWord>]

"Eric A. Hall" <ehall@ehsco.com> wrote:

> Applications can and do define their own domain name syntaxes
> (localpart is different from hostnames, is different from SRV, is
> different from NetBIOS, is different from Kerberos, and so forth).

Maybe you are using the term "domain name" in a more general sense
than the rest of us, but domain names are compared in a particular way
(for example, they are case insensitive) and are subject to certain
constraints (for example, their labels do not exceed 63 bytes).  If an
application's identifiers conform to all the rules for domain names,
they can be called domain names, but if they have their own syntax rules
that are incompatible with domain names (for example, if they are case
sensitive or if they contain strings longer than 63 bytes) then they are
not domain names.

> Under the current wording, all of the applications must use the nameprep
> rules to use IDNA encoding, even if those rules are not applicable to the
> application at hand.

If the email folks want to use something similar to IDNA for email
address local parts, they can.  Their spec can reference IDNA
normatively, borrow from it, or even describe only its differences from
IDNA, but it will be a standard distinct from IDNA.  IDNA itself is for
domain names.

(By the way, the method of representing email address local parts as
domain labels is a limited hack.  It cannot support general email
addresses, only those whose local parts are case-insensitive and no more
than 63 bytes.  When this hack is used, local parts get treated like
domain labels; the domain name syntax rules don't change.)

AMC