RE: Arabic Numbers in the unidode bi-directioanl Algorithm

From: Troy Louden (
Date: Fri May 15 2009 - 15:53:49 CDT

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    Thanks for the quick response. I think I have a clearer understanding now. This brings up a somewhat related question regarding the spec:

    W7. Search backward from each instance of a European number until the first strong type (R, L, or sor) is found. If an L is found, then change the type of the European number to L.

    L N EN => L N L

    R N EN => R N EN

    I took this to mean that the instance of the EN is switched to L only if an L was found, not if SOR or R was found, even if SOR was L, but this seems to generate incorrect results.

    What is the desired behavior of w7 in the case of a string of pure EN numbers (e.g. "123")? Are they all set to L or are they left as EN and bumped to level 2 when resolving implicit levels (3.3.5 table 5)?



    -----Original Message-----
    From: Petr Tomasek []
    Sent: Friday, May 15, 2009 12:22 PM
    To: Troy Louden
    Subject: Re: Arabic Numbers in the unidode bi-directioanl Algorithm

    On Fri, May 15, 2009 at 11:26:16AM -0700, Troy Louden wrote:

    > Hi,


    > I'm implementing the Unicode Bidi algorithm ( for a project at work and I don't understand why, according to the spec, Arabic Numbers are displayed Left-to-Right instead of Right-to-Left.

    Because arabic numerals ARE written left-to-right. (Historically this is

    probably due to the fact, that in arabic the the numbers were read

    starting from the least significant digit, e.g. "three and twenty and hundert"

    for 123...)


    Petr Tomasek <>

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