draft-klensin-idnabis-protocol-04 section 4.5
John C Klensin
klensin at jck.com
Fri Mar 28 13:26:45 CET 2008
--On Friday, 28 March, 2008 06:42 -0400 Vint Cerf
<vint at google.com> wrote:
> this is an area where clarity will help so your assistance is
> John Klensin,
> on the surface, I can see Martin's point. Is there additional
> language in "rationale" that might clear up this uncertainty?
> Or perhaps more needs to be said?
Because MAYBE was removed in some haste, I did not carefully
review all of the relevant surrounding text when it was pulled
out. Clearly, that review must be done and the text updated and
clarified. I will do so as soon as we get the charter settled.
As usual suggestions about text from others would be welcome.
>> This is irrelevant to the charter, but I have difficulties
>> from the citations below how registration is stricter than
>> lookup. Registration only mentions DISALLOWED and UNASSIGNED,
>> whereas lookup mentions NFC, contextual rules, and combining
>> marks in first position on top of that. So I get the
>> impression that lookup is more restricted that registration.
>> What did I get wrong?
>> Regards, Martin.
>> At 21:37 08/03/27, Harald Alvestrand wrote:
>>> From draft-klensin-idnabis-protocol-04:
>>> 4.3. Permitted Character and Label Validation
>>> 4.3.1. Rejection of Characters that are not Permitted
>>> The Unicode string is examined to prohibit characters that
>>> IDNA does
>>> not permit in input. Those characters are identified in
>>> the "DISALLOWED" and "UNASSIGNED" lists that are discussed
>>> in [IDNA200X-Rationale]. The normative rules for
>>> producing that list and the initial version of it are
>>> specified in [IDNA200X-Tables]. Characters that are either
>>> DISALLOWED or UNASSIGNED MUST NOT be part
>>> of labels being processed for registration in the DNS.
>>> 5.4. Validation and Character List Testing
>>> In parallel with the registration procedure, the Unicode
>>> string is checked to verify that all characters that
>>> appear in it are valid for
>>> IDNA resolution input. As discussed in
>>> [IDNA200X-Rationale], the resolution check is more liberal
>>> than that of the registration one. Putative labels with
>>> any of the following characteristics MUST BE rejected
>>> prior to DNS lookup:
>>> o Labels containing code points that are unassigned in
>>> the version of Unicode being used by the application,
>>> i.e., in the "Unassigned" Unicode category or the
>>> UNASSIGNED category of [IDNA200X-Tables].
>>> o Labels that are not in NFC form.
>>> o Labels containing prohibited code points, i.e., those
>>> that are assigned to the "DISALLOWED" category in the
>>> permitted character table [IDNA200X-Tables].
>>> 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
>>> o Labels containing other code points that are shown in
>>> the permitted character table as requiring a contextual
>>> rule ("CONTEXTO" in the tables), but for which no such
>>> rule appears in
>>> the table of rules. With the exception in the rule
>>> immediately above, applications resolving DNS names or
>>> carrying out equivalent
>>> operations are not required to test contextual rules,
>>> only to verify that a rule exists.
>>> o Labels whose first character is a combining mark.
>>> [[anchor15: Note
>>> in Draft: this definition may need to be further
>>> .... more text follows .....
>>>> What I'm trying to understand is what an IDNA200x
>>>> implementation will do
>>>> (i.e., which output string or what error) when the user
>>>> types 'josef゜on'
>>>> or 'dェtェkonsult'.
>>> Read the drafts. It helps.
>>> Idna-update mailing list
>>> Idna-update at alvestrand.no
>> # -#-# Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin
>> # University -#-# http://www.sw.it.aoyama.ac.jp
>> mailto:duerst at it.aoyama.ac.jp
>> Idna-update mailing list
>> Idna-update at alvestrand.no
> Idna-update mailing list
> Idna-update at alvestrand.no
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