Potentially redundant context rules

[Patrik Fältström]

Ok, thanks.

As the IETF week is tiresome for all of us. I will now think, and look  
at this carefully.

If other people have more input though, please do send it to the list.

Hopefully, you will see -06 posted no later than Fri morning. Then I  
unfortunately(?) will be off the net more or less until Wed next week  
as I will take a few days off. So if I do not get time between now and  
Fri morning, you will not see the new draft before Thursday next week.

    paf

On 29 jul 2009, at 14.15, Chris Wright wrote:

> I agree that everything that has been said below is factually correct.
>
> The context rules prohibit Arabic Indic Digits (which have BIDI  
> property AN) from co-existing in a u-label with Extended Arabic  
> Indic Digits (which have BIDI property EN)
>
> BIDI says that ANY DIGITS with BIDI property AN cannot co-exist in a  
> u-label with ANY DIGITS with BIDI property of EN, so the context  
> rules are a redundant subset of the BIDI rules! (Which is why we are  
> arguing for the BIDI rules to be the ones that stay)
>
> I accept that the two rules are not strictly identical, however the  
> argument that the context rules allow ASCII digits to co-exist with  
> Arabic Indic Digits (AN) is irrelevant because as soon as the label  
> contains Arabic Indic Digits it would be subject to the BIDI rules  
> and thus the digit mixing in the label would not be allowed anyway.
>
> Thanks
> c.
>
> -----Original Message-----
> From: Patrik Fältström [mailto:patrik at frobbit.se]
> Sent: Wednesday, 29 July 2009 10:09 PM
> To: Matitiahu Allouche
> Cc: idna-update at alvestrand.no work; Chris Wright
> Subject: Re: Potentially redundant context rules
>
> On 29 jul 2009, at 13.48, Matitiahu Allouche wrote:
>
>> Patrik Fältström asked:
>> "What about the other way around?
>> Is there anything that is covered by Tables context rules that is NOT
>> covered by the Bidi?"
>>
>> Sure!  The context rules for ZWJ and ZWNJ, Geresh and Gershayim have
>> no equivalent in idnabis-bidi-03.txt.
>
> This discussion is about the digits.
>
>> By the way, even the rules for digits overlap between the 2 documents
>> but are far from identical:
>> - In the Tables document, only Arabic-Indic digits and Extended
>> Arabic-Indic digits are mutually exclusive (but can coexist with
>> regular digits in the same label).
>> - In the Bidi document, regular digits (U+0030..U+0039) are mutually
>> exclusive with Arabic-Indic digits, while there is no explicit  
>> mention
>> of Extended Arabic-Indic digits, so by default they will be handled
>> like regular digits since they have the same Bidi type (EN).
>
> Ok, so this seems to imply the rules for the digits are definitely  
> not the same or redundant, as you say Chris?
>
>    paf
>
>> If we call EN the regular digits, AN the Arabic-Indic digits and XN
>> the Extended Arabic-Indic digits, the combinations
>>
>> - EN and AN is disallowed in Bidi and allowed in the Tables
>> - EN and XN is allowed in both documents
>> - AN and XN is disallowed in both documents
>>
>> Seems to me that some more work is needed here.
>>
>> Shalom (Regards),  Mati
>>          Bidi Architect
>>          Globalization Center Of Competency - Bidirectional Scripts
>>          IBM Israel
>>          Phone: +972 2 5888802    Fax: +972 2 5870333    Mobile:
>> +972 52
>> 2554160
>>
>> _______________________________________________
>> Idna-update mailing list
>> Idna-update at alvestrand.no
>> http://www.alvestrand.no/mailman/listinfo/idna-update
>>
>
>

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