Standardizing on IDNA 2003 in the URL Standard

Bjoern Hoehrmann derhoermi at gmx.net
Fri Jan 17 17:11:05 CET 2014


* Andrew Sullivan wrote:
>On Fri, Jan 17, 2014 at 02:23:44PM +0100, Anne van Kesteren wrote:
>> 
>> What's important for interoperability in domain names is translation
>> of a sequence of code points to a sequence of bytes that can be used
>> within the DNS.
>
>This is part of where we disagree.  What is important for
>interoperability is not only what you say, but also a reversible
>translation so that when you get the octets used in the DNS back, they
>can always be turned back into the sequence of code points you started
>with.  IDNA2003 doesn't have that property, which is the reason for
>the backward incompatibility.

I read Anne as saying, for the purposes of this discussion, he cares
about the definition of a `uint8_t* f(codepoint_t* input) { ... }`
function and not user interface or other issues. There was no impli-
cation in the quoted text whether he cares about `f` being injective.
(He might have said something about this elsewhere, but not here).
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