Re: per-paragraph auto-direction, a.k.a. dir=uba

I am modifying the draft to define first-strong exactly as in the UBA.

On Mon, Sep 27, 2010 at 10:28 PM, Aharon (Vladimir) Lanin <aharon@google.com
> wrote:

> Interesting points. I tend to agree that if we see value in first-strong
> being exactly as defined by te UBA, then we should go all the way and make
> the default LTR, not the inherited direction.
>
> Aharon
>
>
> On Mon, Sep 27, 2010 at 10:15 PM, Amit Aronovitch <aronovitch@gmail.com>wrote:
>
>>
>> On Mon, Sep 27, 2010 at 8:31 PM, Aharon (Vladimir) Lanin <
>> aharon@google.com> wrote:
>>
>>> Well, there are two separate issues here. One is that the UBA mangles AN
>>> phone numbers pretty badly. This has no direct impact on the HTML/CSS
>>> proposal. I have no problem sending that in, but would prefer to delay until
>>> after the HTML5 bug submissions are done.
>>>
>>> The other is to get bidi@unicode.org feedback on the modified
>>> first-strong estimation algorithm I am proposing, in the context of the
>>> dir=auto feature (not as a proposal to modify the UBA).
>>>
>>> However, given that fantasai and Mati and Amit have already expressed
>>> reservations about my proposal, and that no one has seconded it, I now
>>> wonder whether it's  worth troubling them over it.
>>>
>>> Aharon
>>>
>>>
>> Supposing you remove the special-casing of the weak-types, then there is
>> still the question of what to do when no strong characters are found -
>> return the inherited direction, or return LTR.
>>
>> The UBA algorithm is only called when there is no "higher level protocol",
>> so it must return something in this "inconclusive" case. The default was
>> chosen to be LTR.
>> However, in our case, we have the option to return the containing
>> element's directionality (at least, I would not consider this option more
>> complicated than the UBA). This would be less disruptive if the element is
>> empty, but has child elements.
>> On the other hand, note that if you return LTR for this case as the UBA
>> does, at least the examples you described (EN dates and negative numbers)
>> would work fine.
>>
>>  Amit A.
>>
>>
>