Re: Errors in TUS Figure 15.2?

From: Antoine Leca (
Date: Mon Aug 02 2004 - 07:12:03 CDT

  • Next message: Peter Kirk: "Re: Errors in TUS Figure 15.2?"

    On Monday, August 2nd, 2004 12:51, Peter Kirk va escriure:

    > On 02/08/2004 09:25, Antoine Leca wrote:
    >>> And there is still a problem with the text before the figure.
    >> Which text?
    > As I wrote before,
    >> There also seems to be an error in the text just before the figure
    >> which states "In the Arabic examples, the characters on the left side
    >> are in visual order already, but have not yet been shaped."

    Ah sorry, I did not pay attention to this. And since Otto (correctly)
    snipped it, a fact I did not notice until now...

    Yes you are right, this appears to be wrongly expressed. Moreover, the
    "original" version in Unicode 3.0.1 (TR#27) already had it. I guess that it
    comes cut&pasted from another source, where there were an additional column,
    at the left, which had some "visual order backing store" content...

    Strange that such a wrong text passed that much reviews.

    > I am looking at this in order to answer an argument that the new
    > proposal which I and a group of others have submitted on Hebrew Holam
    > (L2/04-307, does not
    > conform to the TUS defined use of ZWNJ. Well, it seems that this whole
    > section of TUS is such a mess that it is hard to determine what use
    > actually is defined.

    I do not share this position.

    I am revising this section (and more) while answering PR-37, which is about
    ZWJ. Since I have now spent many hours on this, I have a quite good
    understanding of the issues (even if I cannot say I masterize this area.)

    However, if I can agree with you about the area being fuzzy when it comes to
    *ZWJ* and its numerous uses and some abuses (like Devanagari half-forms),
    the verdict is not anywhere as bad about ZWNJ.
    Behaviour of ZWNJ is consistent in about any place, and the correct
    explanation is the one that is, among others, in chapter 15, that is that
    ZWNJ restricts rendering to unconnected and unligatured forms (or prevent
    use of any connected form or ligature, if you prefer), where possible.

    > Another argument against our proposal is that by defining
    > ZWNJ as breaking a ligature I am specifying implementation.

    This is a dubious argument. Unicode specifies encodings. When two different
    "meanings" are identified, different encodings are requested, so it is a
    task for Unicode.

    OTOH, if there is no underlying difference and the matter is purely of
    presentation (like the aspect of a, like a reversed e or like a o with left
    stem), then Unicode is not to be involved.

    I know the border is fuzzy. ;-) or :-(.

    Here, the fact it ligates or no does mean something (and this is the hard
    part of the demonstration) is what should be examined. How it is implemented
    is largely irrelevant (in fact, it is relevant when the result is *not*

    OTOH, regarding your problem, I should point out that the Bengali's
    precedent is anything but something that should be taken as example: it
    appears to me as an ad-hoc solution built in a hurry, that happened to fit
    well with certain technical implementations; it is a nightmare to handle for
    others; and now there is on the table a proposal, PR-37, which among other
    things will (try to) remove this hack and replace it with another, more
    orthogonal (using ZWJ).


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