Comments on draft-ietf-idnabis-defs-10

Andrew Sullivan ajs at
Tue Sep 1 16:36:53 CEST 2009

On Tue, Sep 01, 2009 at 02:14:37PM +1000, James Mitchell wrote:
> Punycode does not require output to be in any particular case.  I
> have copied from RFC3492 Page 8 below for convenience
> 'An encoder SHOULD output only uppercase forms or only lowercase
> forms, unless it uses mixed-case annotation'
> Therefore KGBECHTV and kgbechtv are both valid outputs of the
> punycode algorithm.

Hrm, so actually it is possible that all ASCII characters in an
A-label are upper case, even though the input from the U-label is not
allowed to have upper case in them.  This seems to be bad, because the
returned result from the Punycode decoding could make the U-label
ASCII characters upper case, right?


Andrew Sullivan
ajs at
Shinkuro, Inc.

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