Updating RFC 5890-5893 (IDNA 2008) to Full Standard

Mark Davis ☕ mark at macchiato.com
Fri Nov 16 21:36:06 CET 2012

I really don't want to revisit all this. It was painful enough the first
time, and people are still extraordinarily sensitive. Saying that someone
was not concerned about backwards compatibility is *not* name-calling.
There are times when it is perfectly legitimate to not be concerned, and
there are often areas where I'm not concerned: typically where the usage is
so low, or the effects are so small, or the benefits are so large, that it
is still worth doing.

Speaking of this, Patrik gives two options:

   1. Backward compatibility with IDNA2003, extend the number of exceptions
   to the algorithm to use, and never ever be able to use ß as a character in
   A- or U-labels.
   2. Using an algorithm based on Unicode Codepoint meta data (from Unicode
   Consortium) to calculate whether codepoints where to be allowed or not,
   take the pain of incompatibility via sunrise for very few code points (like
   ß), but finally acknowledge ß as a character on its own (as Unicode has
   defined it), separate from "ss".

This inaccurately represents #1. More accurate would be:

   1. Use an algorithm based on Unicode Codepoint meta data (from Unicode
   Consortium) to calculate whether codepoints where to be allowed or not*:*
      1. *devise the algorithm so as to maintain compatibility with
      idna2003 as much as possible*.
      2. *maintain the lowercase mappings from idna2003 so that uppercase
      variants still work.*
      3. As with idna2003, ß can be used as a character on input, but
      resolves to the same domain label as when using SS or ss.

Mark <https://plus.google.com/114199149796022210033>
*— Il meglio è l’inimico del bene —*

On Fri, Nov 16, 2012 at 11:18 AM, Paul Hoffman <paul.hoffman at vpnc.org>wrote:

> On Nov 16, 2012, at 6:09 AM, John C Klensin <klensin at jck.com> wrote:
> > I don't want to drag this out, but even that change implies that
> > we dismissed the "backward compatibility" issues as unimportant.
> > That wasn't the case.
> I am someone who, often vocally, disagreed with the way IDNA2008 went with
> respect to backward compatibility. Having said that, I think Mark's
> characterization of the people who were promoting IDNA2008 as "people who
> did not feel that it was an important concern" is simply wrong. The long
> discussions about backward compatibility on the mailing list very much
> showed that the authors were concerned about it and were willing to
> incorporate changes for backward compatibility that had WG consensus (of
> which I was often on the wrong side).
> We have IDNA2003 and IDNA2008 in deployment, both partially. We knew that
> this would happen, we talked about it, and we did IDNA2008 anyway.
> Name-calling at this point is not helpful to developers and end users of
> the two protocols.
> --Paul Hoffman
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