I-D Action:draft-ietf-idnabis-mappings-00.txt

[Paul Hoffman]

At 6:10 PM -0400 5/30/09, John C Klensin wrote:
>On that basis, Martin (and others) have suggested that we be
>selective about the compatibility mappings we support, focusing
>on those that can be typed and have some useful effect and
>avoiding those that, like the above, serve no purpose other than
>possibly to increase risk.
>
>Do you believe there is actually a reason to map those
>characters, as the way you suggest applying NFKC would do?  And,
>if so, can you explain why?

Good questions. The answer is simplicity. Look at Pete's original in the draft. He did NFC plus one additional test ("Full-width and half-width CJK characters are mapped to their equivalents") for which he admittedly hand-waved the mapping. There are probably other "I typed X(a) but I really wanted X(b)" mappings that we would have to add.

The choice is do we want to "just use NFKC" or "use NFC plus a yet-to-be-determined set of additional mappings". I went with the former because of simplicity and getting the protocol done sooner (this might be read as "laziness", I admit). You may not like that tradeoff; however, if that's the case, you need to list the additional mappings that are needed past NFC, the tables we would use for each of those mappings, and how we would know when we are done. (The latter is probably the hardest and could lead us to needing to rename the protocol IDNA2010.)