I don't think there is any disagreement about the J/O split; it is the O characters that we are in a hurry to consider. (I'll send my take in a separate mail.)<br><br clear="all">Mark<br>
<br><br><div class="gmail_quote">On Sun, Jul 19, 2009 at 17:44, Chris Wright <span dir="ltr"><<a href="mailto:chris@ausregistry.com.au" target="_blank">chris@ausregistry.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Accepting that the rationale for these decisions was discussed previously and consensus on the context J/O split was achieved a while ago, does anyone have feedback on the specific issues I raised with each individual context rule then?<br>
<br>
Thanks<br>
<font color="#888888"><br>
Chris<br>
</font><div><br>
-----Original Message-----<br>
From: John C Klensin [mailto:<a href="mailto:klensin@jck.com" target="_blank">klensin@jck.com</a>]<br>
Sent: Sunday, 19 July 2009 1:30 AM<br>
To: Chris Wright; Vint Cerf<br>
Cc: <a href="mailto:idna-update@alvestrand.no" target="_blank">idna-update@alvestrand.no</a><br>
</div><div><div></div><div>Subject: RE: Disallowing code points<br>
<br>
<br>
<br>
--On Friday, July 17, 2009 09:48 +1000 Chris Wright<br>
<<a href="mailto:chris@ausregistry.com.au" target="_blank">chris@ausregistry.com.au</a>> wrote:<br>
<br>
> Vint,<br>
><br>
> I fully support this approach, what I want to point out<br>
> though, is that barring the joiner context rules, no other<br>
> context rules are applied at lookup (and I am not saying they<br>
> should be). Any 'registry' at any level of the DNS hierarchy<br>
> who, either deliberately or through lack of acting diligently,<br>
> does not apply a context rule(s) will still be manifesting the<br>
> problem the context rule was designed to address, as clients<br>
> will still lookup the names!<br>
><br>
> So I still don't fully understand the point of context rules,<br>
> unless they are just going to act as a guide?<br>
<br>
Chris,<br>
<br>
As with any standard that isn't given the force of law<br>
somewhere, all we can do is provide a definition of appropriate<br>
and interoperable behavior. One can hypothesize about<br>
registries (zone administrations) that are evil or sloppy and<br>
one can guarantee that there will be some out there. One can<br>
equally hypothesize about lookup implementations that in order<br>
to save time, code space, because _they_ are evil, or,<br>
conversely, because they want to provide extra protections to<br>
users, apply tests that the standard does not require. That is<br>
less certain to occur, but certainly might (and Gerv's list of<br>
characters that Mozilla has chosen to ban is indicative of the<br>
situation).<br>
<br>
The reason for the distinction between CONTEXTJ and CONTEXTO is<br>
that, the last time the topic was opened, the WG concluded that<br>
there was a difference between a character that required a<br>
specific context but would be reasonably visible as an extra<br>
clue if it was used inappropriately and a character that, in the<br>
wrong context, was invisible or otherwise seriously hostile. I<br>
haven't analyzed how recent discussions and suggested changes<br>
might affect that, but at least originally the distinction also<br>
preserved a higher level of IDNA2003 compatibility -- if strings<br>
were validly registered under IDNA2003 but required context<br>
under IDNA2008, they would still be looked up if they were<br>
assigned to CONTEXTO.<br>
<br>
If you think it would be useful to add some of the above to<br>
Rationale, please suggest text and where to put it.<br>
<br>
Finally, while the protocol police are obviously not out there,<br>
violating a standard in a way that is perceived to cause harm<br>
often does have negative consequences. We've seen browser<br>
vendors blacklist particular characters that were permitted by<br>
IDNA2003. We've seen whole subtrees of the DNS treated in an<br>
irregular way, typically by refusing to display the U-label or<br>
other native character form, because of judgments that relevant<br>
registries did not have acceptable policies. And, while I'm<br>
not aware of its happening with IDNs, there are certainly many<br>
other areas in which violation of established standards and<br>
protocols has been cited in court cases as evidence of grossly<br>
negligent behavior that has led to damage to various parties.<br>
<br>
Is it a perfect solution? No. But the WG did discuss the<br>
tradeoffs --including the possibility of applying contextual<br>
rules to ZWJ and ZWNJ only (not even to a category of which they<br>
are, at present, the only members) and simply making all of the<br>
CONTEXTO characters PVALID or DISALLOWED, with no guidance about<br>
where caution was appropriate -- and concluded that the CONTEXTJ<br>
/ CONTEXTO split was appropriate.<br>
<br>
john<br>
<br>
<br>
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</div></div></blockquote></div><br>