Re: Vertical BIDI

From: Andrew C. West (
Date: Wed May 19 2004 - 06:54:07 CDT

  • Next message: Philippe Verdy: "Re: Vertical BIDI"

    Michael Everson wrote:
    > Come on, people. Read the standard, please. It's on page 338.

    Michael is absolutely right to rebuke me for not reading the Standard. Of course
    I have read the Ogham block intro before, and no doubt that is where I got the
    notion of rendering Ogham BTT from, but I had forgotten that Ogham's BTT
    directionality is explicitly mentioned there. If only I had reread the block
    intro before joining this thread I wouldn't have ended up rambling down a dead
    end in my recent postings.

    But now that I'm back on the marked path the way forward is still as unclear as

    The only thing that is certain is that Ogham must be rendered BTT in vertical
    contexts. For Ogham text in isolation this is fairly easy to accomplish by
    simple rotation, and one could expect "writing-mode : bt-rl" or "writing-mode :
    bt-lr" to accomplish this in a CSS stylesheet. Whether the columns should run
    LTR or RTL across the page is another question, although LTR would be simplest
    to implement as it would only involve rotating a whole block of horizontal LTR
    Ogham text 90 degrees anticlockwise. At any rate, vertical presentation is a
    matter for a higher protocol, and not a Unicode matter.

    However, Ogham text embedded in Mongolian may be a different matter. If a plain
    text editor renders everything horizontally, as most do, then both Mongolian and
    Ogham should be rendered LTR thus <mongolian ogham mongolian>, but if you then
    select vertical presentation (assuming your text editor has this option)
    Mongolian should be rendered TTB and Ogham BTT thus <mongolian mahgo mongolian>.
    I still have no idea as to how this should be achieved. My "hack" of using a
    custom rotated Ogham font and RLO/PDF codes would achieve the desired result for
    vertical presentation, but would make the Ogham text RTL for horizontal
    presentation, which is apparently unacceptable. But what alternatives are there ?


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