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

Patrik Fältström paf at frobbit.se
Fri Nov 16 22:41:06 CET 2012

Offline I have been asked to respond after all, so here we go.

On 16 nov 2012, at 12:36, Mark Davis ☕ <mark at macchiato.com> wrote:

> This inaccurately represents #1.

What is different between what I wrote and what you wrote?

> More accurate would be:
> • Use an algorithm based on Unicode Codepoint meta data (from Unicode Consortium) to calculate whether codepoints where to be allowed or not:
> • devise the algorithm so as to maintain compatibility with idna2003 as much as possible.


> • maintain the lowercase mappings from idna2003 so that uppercase variants still work.

Mapping is not part of IDNA2008, and the need for a 1:1 mapping between A- and U-label is a requirement as outlined in various documents.

> • 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.

I very explicitly did write inability to use ß in an A- or U-label.


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