Standardizing on IDNA 2003 in the URL Standard

[Gervase Markham]

On 16/01/14 11:17, Anne van Kesteren wrote:
> On Thu, Jan 16, 2014 at 10:53 AM, Gervase Markham <gerv at mozilla.org> wrote:
>> UTS46 is, among
>> other things, the mapping layer which IDNA2008 says should be
>> implemented,
> 
> Not is not. Many people in this thread have voiced their opposition to
> UTS46 and the desire to move away from it entirely.

Let me be more precise in my words. IDNA2008 suggests (and in practice
does not work usefully without) an application-level mapping layer,
which it does not define, for things like casefolding. UTS46 is one such
mapping layer, and one with the property that it retains as much
compatibility with IDNA2003 as possible.

>> Fixing on IDNA2003 would permanently block all those scripts which have
>> been added to Unicode since 3.2 (is that right?)
> 
> No that is wrong and that's not how we implement IDNA2003 in Gecko.

Well, that's what IDNA2003 says to do:
https://tools.ietf.org/html/rfc3490#ref-UNICODE

> It's not worse if it's fully backwards compatible and mostly
> interoperable across all major clients. At that point the standard is
> just wrong.

And having a standard fixed to Unicode 3.2 is not also "just wrong"?

> If that was all that had changed, I might be more optimistic. I refer
> you to my earlier email about simple things as lowercasing.

And I refer you to my comments above. Problems like lowercasing (for
better or worse) are punted by IDNA2008 and are labelled as an
application-level problem. In practice, what everyone should do for best
interoperability is implement the same application-level mappings, and
implement ones which are as compatible as possible with IDNA2003.
Hence.... UTS46.

Gerv