Q3: What characters should be allowed in a revised IDNA2008 specification?

Mark Davis mark at macchiato.com
Thu Apr 2 20:34:55 CEST 2009


I agree, and I think there is rough consensus to that effect.

My biggest concern as far as a transitional appendix is not the Hearts and
others, but the cases where IDNA2003 and IDNA2008 produce *divergent*
completely valid A-Labels. For that, I think we must have a very good story
because of security and interoperability issues.

If we have M-Labels (whether full NFKC-CF-RDI or some subset), then it looks
like the sigma and eszett would go away, so that leaves us with only two
cases; ZWJ and ZWNJ. In that case the recommended transitional strategy can
devolve to:

   - Lookup with IDNA2008. If it fails, remove any ZWJ/NJ, and try again.

Mark


On Thu, Apr 2, 2009 at 10:44, Harald Alvestrand <harald at alvestrand.no>wrote:

> I agree with Paul's points below. Let's bite the bullet and say "they
> are invalid under IDNA2008".
>
> Paul Hoffman wrote:
> > At 12:14 PM -0400 3/31/09, Vint Cerf wrote:
> >
> >> Does the working group agree that the more restricted set of the
> >> current IDNA2008 Tables document should apply once IDNA2008 is
> >> adopted?
> >>
> >
> > Yes.
> >
> >
> >> What should be done about registrations that use characters
> >> that would not be allowed under IDNA2008?
> >>
> >
> > Nothing. They will naturally wither as IDNA2008 is adopted by software,
> in the same way that older protocols wither and better ones are deployed.
> >
> >
> >> Should there be a
> >> transitional period of finite duration after which these registrations
> >> will become invalid?
> >>
> >
> > No. They will *always* be valid under the old protocol, and they will
> *never* be valid under the new protocol. There is no reason to blur this
> distinction.
> >
> >
> >> Should they be grandfathered somehow?
> >>
> >
> > No.
> >
> >
> >> If we
> >> believe all future registrations should be restricted, how would such
> >> grandfathered registrations be found if the IDNA2008 rules would
> >> reject lookups of the disallowed characters?
> >>
> >
> > They would be found if we promoted confusion, so let's not.
> >
> >
> >> A two-lookup scheme might solve this problem:
> >>
> >> 1. lookup according to IDNA2008 rules (if disallowed characters are
> >> present, go to step 2); if domain name record is found, return the
> >> information. If not, go to step 2
> >> 2. lookup according to IDNA2003 rules (permitting a broader range of
> >> characters in the lookup process). If domain record is found, return
> >> it, if not return "no such domain name"
> >>
> >
> > Of course. And, as others have pointed out, this scheme creates more
> problems.
> > _______________________________________________
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> > Idna-update at alvestrand.no
> > http://www.alvestrand.no/mailman/listinfo/idna-update
> >
> >
>
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