Additional thoughts on TRANSITIONAL

Erik van der Poel erikv at
Thu Dec 3 19:30:42 CET 2009

Hi Andrew,

I think it's a very interesting proposal, partly because I have also
been thinking about a way to "negotiate" with the server, but my idea
was to start with a default that "works", instead of disallowing
Eszett. My idea, possibly sketchier than yours, is:

Basically, the owner of a label that contains "ss" also "owns" the
equivalent label with Eszett. So the client must "ask" the current
owner (using the "ss" label) if that owner has "released" the
equivalent name with Eszett, and allows another owner to take it. Then
the client can do another lookup with the Eszett name (in Punycode),
and take it from there.

The initial "asking" could be done in DNS, though my thinking was
along the lines of reverse DNS lookup or TEXT records(?). Obviously, I
don't have a very firm understanding of DNS. So my other thought was
to "ask" via HTTP, which has equally obvious downsides.

However, the reason I didn't send this idea to the list is because I
think it is overly complicated on the client side (and there are many
clients, many of which are programmed by engineers who are not as
aware as this WG's participants).

It might be better to try to agree on a dead simple approach, such as:
IDNAbis client implementers agree to stop mapping Eszett to ss, and
ICANN and TLD registries agree not to register names with Eszett
until, say, 2016. We ignore any breakage in the meantime.


On Thu, Dec 3, 2009 at 9:48 AM, Andrew Sullivan <ajs at> wrote:
> Hi,
> I've been thinking more about the TRANSITIONAL approach, and the sort
> of registry-bundle + sunset clause discussion, and I'm wondering if
> the two approaches can't be combined to solve the harms that people
> seem to feel are present especially from ß.  This is a drafty outline
> of how a combined approach could result in the ß being PVALID.  I'm
> concentrating on its case right now because (1) it's a slightly
> simpler problem and (2) it seems to be the case that many think has
> the greatest potential for harm.  If what I am suggesting satisfies
> those who think ß is too dangerous, I think the same strategy more or
> less can be adopted for other problematic cases.  This is extremely
> hand-wavy right now (as it has been in the past when I've described it
> casually to people).  I haven't really worked through the details,
> but if anyone thinks this is a not-insane way out of the current bind,
> then I'll work on it some more.
> I should say to begin with that I view our current problem as
> basically a co-ordinated update problem.  It's impossible to declar a
> flag day.  Those arguing for mapping are basically arging from the
> danger of backward _ambiguous_ compatibility (thanks to Mark for
> putting it so clearly).  I regard that objection as a reasonable one,
> but I am not totally convinced that the solution ("never ever use
> this") is the right answer.  If we had a way to co-operatively
> introduce the characters in a predictable way, then clients could know
> what to do.
> First, the characters we're worried about go into a TRANSITIONAL or
> MAYBE category.  If we call it TRANSITIONAL, then I suggest we set
> some sunset date by which the TRANSITIONAL characters are just
> automatically PVALID, as was already suggested, but I don't feel
> strongly about this.  If we use MAYBE, then this feature is permanent.
> I prefer TRANSITIONAL because it makes this go away (what I'm
> proposing is a kludge).  This would be required immediately, so that
> we could go ahead with the rest of the changes in IDNA2008.
> We write another document about lookups (or just add a restriction to
> protocol) that says how clients looking up these characters might deal
> with them.  The default is refuse, so that the danger that some
> participants see is minimized: there's no ambiguity, but there is a
> failure.  The alternative is to use a mechanism provided by the
> registry in order to decide what to do.  Specifying this is also
> required immediately in order that we proceed.
> Finally, we write a document that outlines how a registry (== zone
> operator) might deal with these characters.  The document outlines
> what bundling, if any, can be done for various characters.  It also
> specifies a format by which a registry can publish its policy on what
> mapping happens.  The location of the policy is places in an SRV or
> NAPTR or some such record.  That allows a client (any client) to find
> the policy as published by the zone operator.  Then the client can
> look up the policy document, find the character in question and see
> how it is mapped.
> Clients can, in this way, be tuned appropriately if desired by local
> users, but they can ship by default with a policy that is tightly
> closed.  As registries come up with mappings, they can publish them
> and the clients that understand this mechanism can react
> appropriately.  Over time, the reaction might even be different (as
> users' expectations come to be different) without us needing to
> re-open the protocol.
> This document does not have to come with the rest of IDNA2008, because
> the default "closed" policy on these TRANSITIONAL characters means
> that they just don't work to begin with.
> The mechanism suffers from some obvious flaws.  First, we're adding
> another lookup plus the obtaining of some policy document to a
> resolution context.  I think this is partly solvable by putting
> expirations on documents and by using longish TTLs on the records.
> We're also adding the potential for a lot of never-to-be-satisfied
> NAPTR or whatever lookups against authority servers, and that's not
> nothing.  It's another pile of stuff to specify, and so these
> characters become delayed while we hammer out this specification.  It
> requires the invention of a way to specify mappings in an
> easy-to-publish and machine-readable format.  It requires more
> infrastructure by sites that want to use the mechanism.
> Nevertheless, it does offer the possibility that both ends of the
> communication can establish (securely, if this is done with DNSSEC for
> the lookup and TLS for obtaining the policy) what the situation is
> with respect to characters in the zone.  This would allow, I think,
> more sophisticated client-side mapping that is desirable to some
> communities where that sophisticaed mapping could be co-ordinated,
> while yet providing a stable and predictable default as some are
> arguing is necessary.  (Once we had the mechanism, we might use it for
> other purposes too -- I originally thought of something like this in
> an effort to attack the "cookie problem", but nobody seemed interested
> so I haven't pursued it.)
> Again, I am aware this is a very sketchy suggestion right now.  That
> stipulated, does it sound remotely sane?
> A
> --
> Andrew Sullivan
> ajs at
> Shinkuro, Inc.
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