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Re: Proposal for isolation characters in Unicode and the unicode-bidi:isolate and unicode-bidi:plaintext definitions

From: Aharon (Vladimir) Lanin <aharon@google.com>
Date: Tue, 3 Jul 2012 16:03:56 +0300
Message-ID: <CA+FsOYYgTzLDf+GkQkbjVe1aXxn7GUZL4fj2cr4k3XzhnTJ_qw@mail.gmail.com>
To: Dov Grobgeld <dov.grobgeld@gmail.com>
Cc: fantasai <fantasai.lists@inkedblade.net>, Matitiahu Allouche <matitiahu.allouche@gmail.com>, asmusf@ix.netcom.com, mohiem@eg.ibm.com, duerst@it.aoyama.ac.jp, public-i18n-bidi@w3.org
Yes, http://www.digipedia.pl/usenet/thread/13266/252/ does seem to go along
the same lines as the present Unicode proposal
thanks for the link. Did anyone actually wind up proposing it to the UTC?

It would be great if the people who were interested in that proposal could
comment on the current one.


On Tue, Jul 3, 2012 at 3:16 PM, Dov Grobgeld <dov.grobgeld@gmail.com> wrote:

> Note the following discussion that discussed something similar back in
> 2004:
> http://www.digipedia.pl/usenet/thread/13266/252/
> Regards,
> Dov
> On Tue, Jul 3, 2012 at 3:07 PM, Aharon (Vladimir) Lanin <aharon@google.com
> > wrote:
>> I have compared the content of
>> http://www.w3.org/TR/2012/WD-css3-writing-modes-20120501/ with that of
>> http://dev.w3.org/csswg/css3-writing-modes/, and I do not think that the
>> changes are at all related to this thread. The isolates are still described
>> in the terms of a higher-level protocol that treats the isolate's content
>> as if it were in a separate document. The list of major changes does not
>> make any reference to Unicode isolates either.
>> Please note that using the new codepoints instead of treating the
>> isolate's content as if it were in a separate document does introduce two
>> significant changes in behavior:
>> - Paragraph breaks (e.g. <br>) within the isolate break the paragraph
>> within which the isolate appears. This appears to be an improvement over
>> the spec as it stands.
>> - The embedding level goes up inside an isolate, instead of being reset
>> to 0 or 1. This is not an improvement over the spec as it stands, but is
>> unavoidable if isolates are implemented in terms of Unicode codepoints.
>> I am not pushing to change the CSS spec now, before the new isolate
>> codepoints have been approved and added to Unicode. I am not at all sure
>> that it can change in this respect until then.
>> However, I do want to make sure of two things:
>> 1. That the CSS spec changes I outlined in my original message look
>> reasonable, so that if the new Unicode codepoints were to be approved
>> today, the spec could be changed as outlined.
>> 2. That the CSS spec of unicode-bidi:isolate, isolate-override, and
>> plaintext will not become frozen before it has been changed to use the new
>> Unicode codepoints.
>> The great benefit for changing the spec to be based on the new codepoints
>> is that it will make it much easier to implement isolates. Current browser
>> implementations have different, serious, difficult-to-solve bugs stemming
>> precisely from the fact that they had to work around the UBA instead of
>> just letting it do its job.
>> It would also be pretty terrible if the Unicode and CSS specs offered
>> very similar features that nevertheless behaved quite differently in
>> certain perfectly valid cases.
>> I would be very happy to discuss the details of the CSS spec changes I
>> proposed. (Actually, if anyone is interested in such a discussion, I should
>> probably start by update that proposal given that both the CSS spec and the
>> Unicode isolates proposal have changed in the meantime.)
>> Aharon
>> On Tue, Jun 26, 2012 at 9:01 AM, fantasai <fantasai.lists@inkedblade.net>wrote:
>>> On 05/17/2012 05:16 AM, Matitiahu Allouche wrote:
>>>> I am in favor of Aharon Lanin's proposal for 3 new characters: LRI, RLI
>>>> and FSI, with Martin Duerst's addition of a fourth
>>>> character to terminate the scope of the last unclosed RI, RLI or FSI.
>>>> I also agree that the HTML/CSS behavior for the BDI element should be
>>>> as similar as possible to the behavior of those 4
>>>> characters in plain text.
>>> I've attempted to work this proposal into the Writing Modes
>>> specification.
>>> Here's the editor's draft:
>>>   http://dev.w3.org/csswg/css3-**writing-modes/#bidi<http://dev.w3.org/csswg/css3-writing-modes/#bidi>
>>> ~fantasai
Received on Tuesday, 3 July 2012 13:04:51 UTC

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