idnabis-defs-10: R-LDH labels that are not prefixed with "xn--"
John C Klensin
klensin at jck.com
Sun Aug 30 20:29:41 CEST 2009
--On Monday, August 31, 2009 4:02 AM +1000 Wil Tan
<wil at cloudregistry.net> wrote:
> Dear IDNAbis WG members,
> First, my apologies for having not noticed or raised this
> earlier.
>
> In idnabis-defs-10 section 2.3.1 paragraph 5:
>
> Labels within the class of R-LDH labels that are not
> prefixed with "xn--" are also not valid IDNA-labels. To
> allow for future use of mechanisms similar to IDNA, those
> labels MUST NOT be processed as ordinary LDH-labels by
> IDNA-conforming programs and SHOULD NOT be mixed with
> IDNA-labels in the same zone.
Unless, in the moving around of text, we have slipped up, it is
important to note that the restriction here applies _only_ to
IDNA-aware applications. That prevents it from being a
restriction on the DNS generally. However, for IDNA-aware
applications, it is a precaution against possible future
prefix-altering changes as well as something of a mechanism for
making it harder for bad guys to game future changes. If any
non-IDNA arrangements come along that use "??--" label
encodings, they will of course have to be coordinated with each
other and with IDNA; in the interim, this provision keeps IDNA
out of their way (i.e., avoids preempting such approaches).
And, yes, the WG did discuss this at great length.
> I may have missed it, but don't recall any discussions about
> restricting the processing of other tagged domains. Is this
> the right draft to prescribe restrictions on how non-XN-Labels
> are processed?
IMO, we are much too tied up in special definitions and
confusing terminology already. Please let's not make it worse
by introducing more unnecessary terminology in the form of
"tagged domains". And it is the right place for defining how
IDNA-aware applications handle R-LDH labels that are not valid
A-labels, at least IMO and in the opinion of the mailing list
the last two or three times we went through that topic.
best,
john
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