Re: Vertical BIDI

From: fantasai (
Date: Tue May 18 2004 - 21:35:30 CDT

  • Next message: John Cowan: "Re: Vertical BIDI"

    Philippe Verdy wrote:
    >>What's uncertain is whether a lr or a rl progression is favored, given the
    >>paucity of evidence. Michael favors lr progression. There is no question
    >>that the text is read BTT.
    > This creates an interesting problem: Put in the same sentence Han (Chinese) and
    > Mongolian words in a vertical layout (I don't think this is unlikely, as
    > Mongolian is also spoken in China, and there's also a Chinese community in
    > Mongolia). So Chinese ideographs will be laid out vertically from top to bottom
    > (but not rotated, except for a few characters like ideographic punctuation marks
    > or symbols), and Mongolian will be laid out from bottom to top in their normal
    > stack orientation. Such a text is clearly bidirectional, so we would need BiDi
    > processing to order glyphs correctly.

    I don't understand this scenario. Mongolian is laid out from top to bottom when
    in vertical lines, *always*. /Ogham/ is what would go bottom to top, and yes,
    that would create a different BIDI scenario than that found in horizontal text.

    > So what is shown here is that Bidi properties are only accurate for horizontal
    > flows of text. What is missing is a separate set of Bidi properties for the
    > vertical direction of the same flow... We could define basically a similar
    > algorithm for vertical BiDi, but this would also require new BiDi properties.

    This is what I've tried to argue, but for different script combinations than
    you are describing here: the directions of Mongolian and Han do not conflict
    in vertical text.



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