[css3-text-layout] text-combine for Bopomofo case

(As my previous post is lost somewhere I am posting this again, with small edits)

I noticed text-combine does not support very similar phenomenon that happens with Bopomofo used in Taiwan.

The following is an example. The portion in red is one phrase consisting two words (I heard it means "mouth watering"). While the text goes horizontal, the first word is in Bopomopho laid out vertically in the line height.
http://www.flickr.com/photos/67381643@N00/5069541651/

This is essentially the same with tate-chu-yoko (horizontal-in-vertical) except it is vertical-in-horizontal.

With both cases it happens when a script that is strongly horizontal or vertical is laid out in a different direction, and in its native direction it just behaves normally. The current "upright" value captures this for horizontal-in-vertical by saying, "In horizontal mode this value is equivalent to ‘none’.". I believe we need a separate value to support vertical-in-horizontal case such as Bopomofo.

Considering both cases are actually upright, I suggest renaming "upright" to "horizontal" and add "vertical" to support the vertical-in-horizontal case. The values mean the composition should always be in horizontal or vertical.

- kida

# Is [css3-text-layout] the recommended mail subject or should it be updated to [css3-writing-modes] ?