comments on draft-ietf-idnabis-bidi

Erik van der Poel erikv at google.com
Tue Aug 4 02:25:37 CEST 2009


I have tested this new set of rules with domain names up to 9
characters and they work for both the Label Uniqueness and Character
Grouping requirements.

Erik

On Mon, Aug 3, 2009 at 4:34 AM, Harald Tveit
Alvestrand<harald at alvestrand.no> wrote:
> Matitiahu Allouche skrev:
>> In my previous suggestions, I did not take in consideration that the rules
>> are meant to codify also labels which do not contain any RTL characters.
>> Having understood that, here is an updated version of my suggestions:
>>
>> Definitions:
>>
>> 1. Bidi domain names are domain names which include at least one RTL
>> label.
>>
>> 2. A RTL label is a label which contains at least one character of type R
>> or AL or AN.
>>
>> Rules for RTL labels in Bidi domain names:
>>
>>    1.  Only characters with the BIDI properties R, AL, AN, EN, ES,
>>        CS, ET, ON, BN and NSM are allowed in RTL labels.
>>
>>    2.  The first position must be a character with Bidi property R or AL.
>>
>>    3.  The last position must be a character with Bidi property R, AL, EN
>>        or AN, followed by zero or more NSM.
>>
>>    4.  If an EN is present, no AN may be present, and vice versa.
>>
>>
>> Rules for non-RTL labels in Bidi domain names:
>>
>>    1.  Only characters with the BIDI properties L, EN, ES,
>>        CS, ET, ON and NSM are allowed in non-RTL labels.
>>
>>    2.  The first position must be a character with Bidi property L.
>>
>>    3.  The last position must be a character with Bidi property L or EN,
>>        followed by zero or more NSM, or the two last positions must be
>>        EN followed by ET.
>>
>>
>>
> Thank you again - I have now implemented this algorithm and compared the
> result for the "Character Grouping Requirement" up to a length of 3
> characters (my perl code is chugging on longer strings as we speak).
>
> I hope Erik can take a look at the "Label Uniqueness Requirement", which
> I don't have code to test for.
>
> The difference between the two algorithms seems to be that your proposal
> allows CS and ET within a label, but not at the ends. Was this an
> intentional difference?
>
>                  Harald
>
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