browser behavioral differences for IDNA

"Martin J. Dürst" duerst at
Wed Oct 28 10:56:55 CET 2009

Hello Mark,

On 2009/10/22 4:51, Mark Davis ☕ wrote:
> FYI, UTS 46 points to differences among browsers regarding separator
> (period) behavior. See

[Side note: I think it's not helpful to have sentences such as "While 
%2E is outside of the scope of this document," followed by long 
explanatory text, in a tech report that should be usable as a spec. 
Unfortunately, my impression is that the UTC process seems to lead to 
more such text accumulating than some other processes.]

> Markus and I have further investigated some browser behavior, and have also
> found differences regarding normalization behavior for IDNA. See:

This is very interesting, in particular in two respects:

a) For each corrigendum, at least some of the implementations seem to 
have adopted it. I very much hope the others will follow. On the IDNAbis 
WG list, some people pointed out that if there were RFC errat for the 
Unicode corrigenda, that would help implementations. I can submit some 
errata if people thing that indeed will help.

b) The entry "FF - 3.2 -- applied twice!" confirms what I have been 
claiming since the very time the Normalization Idempotency bug was 
found: That the IDNA spec (implicilty) assumed that normalization was 
idempotent, and than different implementations might end up with 
applying normalization once or twice, and thus differ in their result on 
those cases where (before the corrigendum) normalization wasn't 
idempotent. All the more reason to apply this corrigendum via an RFC 

BTW, what is Opera doing?

Regards,   Martin.

> Mark
> On Tue, Oct 20, 2009 at 12:24,<announcements at>  wrote:
>> The draft UTS#46 Unicode IDNA Compatible Preprocessing has been updated.
>> There are a number of new review notes pointing out issues and asking for
>> feedback. There are also new tables: one comparing behavior of compatibility
>> and escaped versions of FULL STOP in delimiting labels between different
>> browsers, and one comparing the allowed and disallowed repertoires when
>> processing IDNs according to the IDNA2003, IDNA2008, and UTS #46
>> specifications. There are also many improvements and clarifications of the
>> text.
>> See:
>> Review period closes October 26, 2009.
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#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-#   mailto:duerst at

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