Unicode 5.2 -> 6.0

[John C Klensin]

--On Thursday, October 14, 2010 13:22 -0700 Tina Dam
<tina.dam at icann.org> wrote:

> Hi Patrick, thanks for this. It was sooner than I expected...
> 
> In terms of the forward progress, I agree with your
> recommendation for the specific example. Generally I think in
> order to choose between the options (accept change or add
> exception for backward compatibility) I would personally like
> to hear from registries that have implemented the character
> and who may be disadvantaged by it's elimination.

Tina, I know you know this but, just as it is sometimes easy to
lose sight of the fact that the DNS is not just about "web
addresses", it is sometimes easy to lose track of the depth and
extent of the tree.  The meaning of "registry" in IDNA2008 (and
similar terminology in IDNA2003) extends to every zone
administrator of a zone in the DNS.  In principle, the
administrator of a subdomain somewhere deep in the DNS tree
could have chosen to utilize one or more of these characters
without having to discuss that decision with anyone else.

While I believe that the probability of that having occurred is
actually very low, any sort of decision process associated with
"ask the registries" or "hear from the registries" has most of
the properties of a search for a universal negative: if someone
comes forward and says "yes, I am using one of those" it gives
us a lot of information but that absence of such an answer tells
us almost nothing... and, in this day of restrictions on zone
transfers, there is no feasible way to walk the entire tree.

> For this specific case, I am personally unaware of any IDNs
> with the New Tai Lue script. However, we should probably make
> some sort of process where the gTLD registries and ccTLD
> registries are asked to provide relevant input if/when this
> happens again.

While I think some mechanism of that sort would be a good idea,
we also need to remember that, while many people are thinking
about IDN TLDs in terms of script-homogeneous or
language-homogeneous trees and FQDNs, there is, in general, no
plausible way to enforce such requirements.  Even if one could
do that for IDN TLDs and their subtrees, it is not possible for
subtrees of existing, non-IDN, TLDs.

best,
   john