What rules have been used for the current list ofcodepoints?

[Martin Duerst]

At 07:43 06/12/15, John C Klensin wrote:

>(3) We cannot establish a principle that strings coming into IDNA (or Nameprep) must already be normalized (to NFC at least). The rule that NFKC(cp) must equal cp is well and good, but, taken by itself,  I think it eliminates all sequences involving combining characters for which there are precombined sequences

As far as I understand, the rule is only on single codepoints.
As such, my understanding is that it only affects singleton normalizations.
Any usual base characters will survive, and any combining character
will survive (because alone, it is in NFKC). So it doesn't eliminate
all sequences involving combining characters for which there are precombined
sequences, on the contrary, it leaves in all of these so that they
(or most of them; in a few cases, the decomposed and not the precomposed
sequence is NFC/NFKC) have to be normalized or excluded in a separate step.

>and may have some other ill effects.

Anything in particular you are thinking of?

Regards,     Martin.



#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst at it.aoyama.ac.jp