Shawn.Steele at microsoft.com
Thu May 8 22:59:13 CEST 2008
> This also neatly solves the problem of whether or not IDNA-unaware and
> IDNA-aware clients are allowed to look up labels with Punycode in
> them. They should always be allowed to do so. Only software that tries
> to convert from U-labels to A-labels needs to be restricted. This is
> how we can achieve the most reasonable level of interoperability, in
> my opinion.
I think that conversion U to A conversion does NOT need restriction. Assuming that the steps in conversion include NFKC or appropriate mappings, then if a character moves from disallowed to allowed, the conversion is already known. So no change is required for lookup, even if conversion is required. The only change would be the software the decides the legality of the name, which, IMO could be at a different layer.
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