draft-klensin-idnabis-protocol-04 section 4.5

[Vint Cerf]

martin,

this is an area where clarity will help so your assistance is  
appreciated.

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?

v

> This is irrelevant to the charter, but I have difficulties  
> understanding
> 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:
>>
>> (registration)
>>
>> 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.
>>
>> (lookup)
>>
>> 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
>>      present.
>>
>>   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 tightened.]]
>>
>> .... 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.
>>
>>                 Harald
>>
>>
>> _______________________________________________
>> Idna-update mailing list
>> Idna-update at alvestrand.no
>> http://www.alvestrand.no/mailman/listinfo/idna-update
>
>
> #-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
> #-#-#  http://www.sw.it.aoyama.ac.jp        
> mailto:duerst at it.aoyama.ac.jp
>
> _______________________________________________
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