[idn] Stringprep and UAX15

["Hollenbeck, Scott" <shollenbeck@verisign.com>]

Last Tuesday I sent this to the list:

http://www.imc.org/idn/mail-archive/msg05544.html

The stringprep draft contains this text at the end of section 4:

"A profile MUST refer to a specific version of [UAX15]. If a later version
of [UAX15] changes the algorithm used for normalization, that later version
MUST NOT be used with the same version of the profile."

Followed by this unanswered question:

"Patrik asks: Is not addition of unassigned codepoints regarded an update of
UAX15? This is relevant here."

I've yet to see a response to my original query.  Assuming that assigning
codepoints that were previously unassigned would require an update to
Unicode 3.1.0, and UAX15 very clearly lists the normative Unicode version as
3.1.0, perhaps the answer to Patrik's question is "yes" -- UAX15 would need
to be updated (though the normalization algorithm itself might not change),
but as described in UAX15 backward compatibility would have to be preserved.

Would it make sense to add something like this to the end of section 4
(perhaps prior to the "A profile MUST" sentence) to answer Patrik's
question:

"The composition process described in [UAX15] requires a fixed composition
version of Unicode to ensure that strings normalized under one version of
Unicode remain normalized under all future versions of Unicode."

If I've missed the mark I'll apologize in advance.  No matter what, though,
Patrik's question needs to be removed from the draft and either text should
be added to answer the question or someone should explain why the question
is irrelevant.

-Scott-