Re: [idn] IDN rechartering rev 3, and nameprep

[David Hopwood <david.hopwood@zetnet.co.uk>]

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Dave Crocker wrote:
> 
> There has been no further discussion about the revised charter, for more
> than one week.  That suggests that it is time to adopt it and send it to
> the IESG.

> Goal & Milestone:
> Nov 2001        domain name identifiers normalization draft last call

This is completely unrealistic. There are many unresolved issues concerning
normalisation.


Here is one of them: the current nameprep draft doesn't always produce
identical results for two canonically equivalent names.

For example, "\u1F70\u0345" and "\u1FB2\u0300" are canonically
equivalent strings representing 'alpha with varia and ypogegrammeni'.
However:

  NFKC(fold("\u1F70\u0345")) = "\u1F70\u03B9" (alpha-varia, iota)
  NFKC(fold("\u1FB2\u0300")) = "\u1F70\u1F76" (alpha, iota-varia)

This could be fixed by using the "simple" versions of case foldings for
characters that include ypogegrammeni or prosgegrammeni, and removing
the folding for U+0345. (It isn't actually important to consider
ypogegrammeni to be equivalent to iota, but uniform treatment of
canonically equivalent strings is definitely important.)

Other issues relating to normalisation are:
 - whether to use NFKC or NFC
 - what set of characters to disallow (the current spec arguably
   allows too much)
 - treatment of Hangul compatibility Jamo
 - the point raised by Kent Karlsson about Jamo clusters
 - the definition of "stored" and "request" strings in stringprep

I frankly don't see how normalisation can be finalised without knowing
which protocol proposal will be used, or why it's necessary to finalise
it before then.

- -- 
David Hopwood <david.hopwood@zetnet.co.uk>

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