IDNA applications (was: RE: sharp s (Eszett))

John C Klensin klensin at
Sat Mar 8 00:13:18 CET 2008

--On Friday, 07 March, 2008 14:32 -0800 Paul Hoffman
<phoffman at> wrote:

> Following up on my own posting:
> At 2:19 PM -0800 3/7/08, Paul Hoffman wrote:
>> This goes back to a comment you made earlier today about the
>> way I  stated "(a)". I said:
>> a) Update base character set from Unicode 3.2 to Unicode 5.0
>> or 5.1
>> You said:
>> a) Update base character set from Unicode 3.2 to Unicode
>> version-agnostic
>> Those two are quite different statements, and the group needs
>> to  decide which, if either, it wants to achieve.
> Looking at the proposed charter again, it says both (a) and
> (b).

I think that, when I first glanced at the draft charter, I took
"(a)" to mean "make sure we end up at least as 5.0 or 5.1" and
the comment at the end as the goal.   

My personal view --and I want to stress that it is just a
personal view-- is that a decision to upgrade to a specific
version of Unicode only would be equivalent to rejecting the
general approach in the IDNA200X documents.  In addition, based
on experience with IDNA2003 implementations using libraries that
do not report Unicode versions, I do not believe that a decision
to simply switch from hard-binding from one Unicode version is
plausible.   Part of that issue was discussed at length in RFC
4690 which, while not formally an IETF consensus document,
should not be a surprise to anyone on this list.   I believe
that the "unassigned code point lookup" issue, the prohibition
on display of punycode-encoded strings, and the idea of a strong
tie to a particular version of Unicode all constitute known
technical deficiencies in RFC 3490 and friends, in the sense
that phrase is used in RFC 2026.

> . . . 
>> This WG
>> is chartered to untie IDNA from specific versions of Unicode
>> using algorithms that define validity based on Unicode
>> properties.
> We need to clear this up in the charter depending on how the
> group wants to go.

For the reasons outlined above, in 4690, and in the existing
documents, I do not personally believe that there is any real
"clearing up in the charter" for any reason but clearing up the
ambiguity that you have pointed out.   The assumption of Unicode
version independence is strongly enough embedded in the IDNA200X
documents that, if the group doesn't "want to go" that way, I do
not believe that the existing documents are usable as a base and
one would need to think about an entirely different charter and
set of benchmarks.


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