Touchstones for "Mapping"

Vint Cerf vint at
Thu Apr 2 14:50:13 CEST 2009


I continue to be somewhat confused by logic that suggests that storage benefits from being in the U-label form.   A-labels are almost de facto normative since they work withIDN-aware and IDN-unaware appllications. IDN-aware applications should be able to generate the corresponding U-label for presentation. IdN-unaware applications. Won't even recognize a U-label domain name as valid IWoild think. Consequently, storage in A-label form seems the rational choice. If you disagree, it must be because you see a flaw in the reasoning above. Can you clarify? V

----- Original Message -----
From: idna-update-bounces at <idna-update-bounces at>
To: Harald Alvestrand <harald at>
Cc: Andrew Sullivan <ajs at>; idna-update at <idna-update at>
Sent: Thu Apr 02 03:37:30 2009
Subject: Re: Touchstones for "Mapping"

There are two sides here, the protocol correctness and
the content correctness. By content correctness, I mean
whether the link e.g. goes to the intended page.
Completely impossible to check with punycode, of course.

Regards,   Martin.

On 2009/04/02 16:56, Harald Alvestrand wrote:
> Martin J. Dürst wrote:
>> I very much agree with Harald. We are working on IDNs because we want
>> humans to be able to easily read domain names in their script. Storing
>> them as A-Labels when there is a reasonable chance that humans will
>> have a look at them (e.g. in HTML or XML source, email source,...)
>> is against the very intent of IDNs. Authors are humans, too, even
>> if they work on plain text :-!
> I can argue the other side of the argument for HTML and XML, though.....
> the main thing being that humans who *enter* IDNs in Unicode form
> without the benefit of conformance-enforcing software interfaces will
> just about always get them wrong (due to bizarrities of case,
> compatibility characters and other weirdnesses).
> If they enter A-labels by hand, it's pretty certain they've
> cut-and-pasted them.
>               Harald
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#-# Martin J.Dürst, Professor, Aoyama Gakuin University
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