Codepoints removed between IDNA200X and IDNA2003

John C Klensin klensin at
Wed Mar 19 13:20:55 CET 2008

--On Wednesday, 19 March, 2008 16:05 +0900 Martin Duerst
<duerst at> wrote:

> Patrik - There is clearly some problem with the start of this
> table. Control characters were never allowed in IDNA2003,
> neither such things as "!", and basic ASCII upper case letters
> are probably still allowed in IDNABIS.

Nope.   The "no mappings in the protocol" rule is applied with
absolute consistency.  And, because case folding is not
equivalent to lower casing in many cases (leading us into the
debates we have seen with Eszett and Final Sigma), the case
mapping situation is fully as problematic as compatibility


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