Updating RFC 5890-5893 (IDNA 2008) to Full Standard

Anne van Kesteren annevk at annevk.nl
Thu Nov 8 10:05:59 CET 2012

On Thu, Nov 8, 2012 at 6:45 AM, "Martin J. Dürst"
<duerst at it.aoyama.ac.jp> wrote:
> By chance, I found the reference that I was referring to again:
> http://annevankesteren.nl/2012/09/idna2008

I'm not sure what Internet Explorer does, but of the other browsers
only Opera implements IDNA2008 (and does not do it per the
recommendations of UTS #46, and is probably incompatible with deployed
content and needs to change).

The main problem with IDNA2008 is that it makes a large corpus of
domain strings effectively undefined, since it does not define
pre-processing between e.g. finding an domain string in a page and
applying the relevant algorithms and does not forbid such an algorithm
either. In particular http://tools.ietf.org/html/rfc5891#section-5.2
is very handwavy whereas IDNA2003 is perfectly clear.

Overall, making backwards incompatible changes to domain string
processing seems wildly inappropriate and I wonder why the IAB did not
intervene. The rationale document cites "surprising" and "sensible"
but I think we need something stronger to invalidate running code.
(And if we don't, then the arguments I get about URI/IRI seem out of


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