From: fantasai (email@example.com)
Date: Mon May 17 2004 - 14:34:58 CDT
Ernest Cline wrote:
> John Cowan wrote:
>>Andrew C. West scripsit:
>>>Thus, if "tb-lr" were supported, your browser would display the
>>>following HTML line as vertical Mongolian with embedded Ogham
>>>reading top-to-bottom, but in a plain text editor, the Mongolian and
>>>Ogham would both read LTR, and everyone would be happy :
>>I don't know about that. I wouldn't be too happy trying to read English
>>with the Latin letters laid out bt-rl and lying on their left sides to
>>On paper is one thing, but on a non-rotatable screen? I don't think so.
> Which may well be why CSS doesn't have "bt-rl" (It was in an early
> draft, but the actual recommendation does not support "bt-lr" or "bt-rl".)
> The lack of actual scripts that have a bottom to top block progression
> (as CSS would describe it) probably also played a part.
Block progression is the direction subsequent lines are laid out;
tb block progression is like that found in English, rl like Chinese,
lr like Mongolian.
In the last version, 'writing-mode' is a shorthand for two other properties
and doesn't reflect the full range of their combinations. You could effect
bt-rl with the individual properties, if you wanted to.
> Still, this whole question of what to do with the glyphs when a text is
> written in an unusual orientation is something that must be answered.
> Whether the answer should be given by Unicode is a related but
> separate question. CSS glyph orientation  is an attempt at an
> answer, but whether it is sufficient I can't say as I haven't dealt with it
> in any detail myself.
>  http://www.w3.org/TR/css3-text/#GlyphOrientation
CSS3 Text's glyph orientation isn't designed very well. It does weird things
like displaying Arabic text (horizontally) upside-down when English text is
still right side up. 
Also, please note that the CSS3 Text Candidate Recommendation is a good
candidate for being pulled back to working draft status, so it should
not be considered stable. The text layout section has a lot of problems,
especially with the interaction of the different properties defined in it.
(Like most mixed-script suggestions on this list, it requires fiddling with
bidi overrides to get correct rendering in far too many modern cases;
because of the Cascade in CSS, that workaround is a messy and problematic
As for Unicode, Unicode should not say which way the line is facing; that's
the formatting language's prerogative. Given a direction, however, Unicode
should say how the characters within a line should be ordered. The ordering
differs depending on whether horizontal scripts' tops are facing the top of
the page, the left of the page, or the right of the page. Right now only the
"facing top" case is properly defined.
Note: Which way the line faces is different from which way it stacks (also a
stylistic property). Latin names in Mongolian, for example, often face
to the right, same as in Chinese, even though the line stacks from left
to right, not right to left. 
(Multi-Script Dictionary, Taiwanese Booklet, Translating Genji)
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