Re: [css3-text-layout] margin-before/after/start/end etc. and :ttb pseudo-classes

> 
> I am not sure I understand what is the problem and what complexities
> you are talking about.

OK.  Let me try again.

At present, we have (1) writing-mode specified in stylesheets, (2) the ability 
of browsers, and (2) the writing mode chosen by users.  If we introduce 
@dir="ttb", etc., we will have (4) the writing-mode specified in documents. 
We have to define conflict resolutions; for example, what happens when @dir="ttb", 
the writing-mode property is "rtl", and the user choose "rtl"?  It may be certainly 
possible.  But I am not sure if we need (4).

Cheers,
Makoto