Parsing the issues and finding a middle ground -- another attempt

Andrew Sullivan ajs at shinkuro.com
Tue Mar 3 21:46:19 CET 2009


On Tue, Mar 03, 2009 at 03:27:11PM -0500, John C Klensin wrote:
> >> (iii) We tell folks on the lookup side that, if a label in
> >> native-character form is invalid under IDNA2008 but valid
> >> under IDNA2003, they SHOULD apply the IDNA2003 mappings and
> >> look the thing up.  Note that this implies two tests but only
> >> one lookup in the DNS. ...
> > 
> > If we made that a MUST, I'd be happy with it. If it is not a
> > MUST, then we can always have two kinds of implementations,
> > which will inevitably cause some interoperability problems.
> 
> I said "SHOULD" because, in IETF-speak, MUST implies that there
> are no exceptions and, in particular, no cases in which an
> implementation (or application specification) might reasonably
> insist on a "no mapping" approach for absolute precision about
> what is being done.

What about something along these lines:

    If a label in native-character form is invalid under IDNA2008 but
    valid under IDNA2003, an application SHOULD apply the IDNA2003
    mapping, and MUST apply the IDNA2003 mapping by default.
    Applications MAY provide a mechanism to disable the IDNA2003
    mappings according to local policy.  Applications MUST NOT use any
    other mapping.

?  I kind of hate this (and it's unenforcable anyway), but is it is
roughly what you're both aiming at?

A

-- 
Andrew Sullivan
ajs at shinkuro.com
Shinkuro, Inc.


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