Stability of valid IDN labels

John C Klensin klensin at
Tue Apr 22 19:32:50 CEST 2008

--On Tuesday, 22 April, 2008 18:57 +0200 Patrik Fältström
<patrik at> wrote:

> On 22 apr 2008, at 18.52, John C Klensin wrote:
>> If the Unicode decision were to make a
>> change, there would be adequate time to review whether the
>> codepoint should be added to the exception list to keep its
>> IDN behavior stable.
> John is absolutely correct, and I want to support what he says
> about timing, how heavy the process is etc. But, I need to
> correct one small thing. We have in the tables document a
> special "Backwards compatibility list" that works exactly like
> the exception list, but is a different (now empty) table. This
> so developers very clearly can see what are the "kind of"
> overrides that are made for this specific reason.
> Of course, if people do not think that is needed, I want to
> know... But the *current* document has exactly this feature.

FWIW, I believe that keeping the "backwards compatibility list"
separate from the "exception list" is a good idea.  Sorry for
oversimplifying in a way that might have created confusion.


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