Re: [css-writing-modes] RTL scripts in vertical text

On 05/08/2014 04:40 AM, James Clark wrote:> The Unicode Bidi spec [1] describes two ways of handling
> RTL scripts in vertical writing modes.
> (a) Use these levels not to reorder the line, but instead
> to determine whether to rotate sideways left or sideways
> right, so that the line is uniformly ordered from top to
> bottom:
> [...]
> I see how to do (b) with the current spec, but I don't see
> how to do (a) (without explicitly marking up each bidi run).
> I was wondering whether this capability was omitted
> intentionally, and, if so, why.

This was indeed omitted intentionally, largely because technique (a)
really does not work well with real-world text. Consider, for example,
that numerals are LTR. What would happen is that if you had a fragment
of Arabic or Hebrew containing numbers (such as a version number, a
date, etc.) part of the phrase would be rotated clockwise and part of
it counter-clockwise. The same thing would happen with embedded Latin
names and acronyms (e.g. OPEC, USA, etc.)

The resulting layout is very awkward to read.

It is better, if this technique is wanted, for the author to explicitly
mark up runs and rotate the entire run (including both its LTR and RTL
contents) in a single direction.

Let me know if this answers your question.


Received on Tuesday, 25 August 2015 00:08:08 UTC