New versions of Protocol (-04) and Rationale (-02)

John C Klensin klensin at jck.com
Sun Sep 14 19:41:50 CEST 2008



--On Friday, 12 September, 2008 17:26 -0700 Erik van der Poel
<erikv at google.com> wrote:

> Hi John,
> 
> Thanks for posting the new Protocol and Rationale.
> 
> 5.4.  A-label Input
> 
>    If the input to this procedure appears to be an A-label
> (i.e., it    starts in "xn--"), the lookup application MAY
> attempt to convert it    to a U-label and apply the tests of
> Section 5.5 and, of course, the    conversion of Section 5.6
> to that form.  If the A-label is converted    to a U-label
> then the processing specified in those two sections MUST
> yield an A-label identical to the original one.
> 
> It might be a bit clearer if the final sentence is changed to:
> "If the label is converted to Unicode using the Punycode
> decoding algorithm, then the processing specified in those two
> sections MUST be performed, and the label MUST be rejected if
> the resulting label is not identical to the original."

Definitely better, IMO.  Changed unless someone objects.

>    Putative labels with any of the following
>    characteristics MUST BE rejected prior to DNS lookup:
>    [...]
>    o  Labels containing code points that are shown in the
> permitted       character table as requiring a contextual rule
> and that are       flagged as requiring exceptional special
> processing on lookup       ("CONTEXTJ" in the Tables) MUST
> conform to the rule, which MUST be       present.
> 
> This item is not worded as a "characteristic" that "MUST BE
> rejected" (as the introductory text says above). How about
> rewording it to:
> 
> Labels containing code points that are shown in the permitted
> character table as requiring a contextual rule and that are
> flagged as requiring exceptional special processing on lookup
> ("CONTEXTJ" in the Tables) but do not conform to that rule.

Change made.  Anyone who doesn't like it should speak up.

I will wait at least a couple of days for more comments before
posting -05.

    john



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