Re: Boustrophedon

From: Asmus Freytag (
Date: Wed Nov 05 2008 - 23:54:33 CST

  • Next message: Murray Sargent: "RE: Mirrored ASCII"

    On 11/4/2008 6:07 AM, Doug Ewell wrote:
    > Q: Why is this thread like boustrophedon itself?
    > A: Because it goes in two different directions.
    > It would be really neato if we could split the "principles of
    > boustrophedon" discussion off into a separate thread, called, oh, I
    > don't know, maybe "Re: Boustrophedon", and leave the present Subject
    > line for discussions that really do have to do with Old/Szekler
    > Hungarian.
    Q: Why don't people write that mirroring happens all the time with

    A: (Most likely): We are talking about how people write. Even modern
    scribes (not typist) are not all uniform in (not) applying mirroring to
    Latin. I only have to look at the letters my 7-year old writes to her
    grandmother ;-)

    But seriously, when it comes to a specific collection of hand-written
    materials, you can't necessarily tell with perfect accuracy whether what
    the scribes did or didn't do was accidental, personal idiosyncrasy or
    accepted variation. The only thing you can be 100% sure about is noting
    down everything you do encounter.

    Q: Why does Unicode's bidi specification intersect with rendering
    ancient scripts?

    A: The bidi specification has two parts, an implicit part and an
    explicit part. The implicit part handles whether a script is by default
    RTL or LTR, and the interaction with *shared* punctuation marks and
    modern digits. The explicit part is where the author can assign
    directionality to a run of text.

    Because of the needs of modern bidi scripts, these mechanisms are widely
    supported in tools and on the web. If you want to publish ancient texts,
    and if you can fit into these existing solutions, then you're done (plus
    or minus having a font available for yourself and recipients of
    non-final form documents, such as HTML).

    HTML, CSS etc. take over part of what the explicit part of the bidi
    specification can do, and replace it with commands in their own syntax.
    Generally, the results could still be copied out as plain text,
    preserving the bidi settings as explicit bidi format characters.

    Q: Do we need a boustrophedon setting for HTML, CSS etc?

    A: The problem with using existing bidi formatting for boustrophedon is
    that you lose automatic line wrapping. You have to decide ahead of time
    where your line ends, and insert format characters to define the
    directionality of the following line. That may be fine for *exactly*
    representing ancient originals, but it's a poor approach for showing
    general texts in a matter that preserves the spirit of boustrophedon,
    but works in the modern typographic environment.

    Honestly, it is unclear at this moment how important that functionality
    is - but unless it becomes a part of these protocols (and widely
    supported) it will be difficult to widely disseminate such texts
    formatted in this manner.

    Q: Why is the specification of bidi/mirroring important?

    A: The way mirroring is defined in bidi is all-inclusive, with the few
    exceptions limited to LTR scripts shown as RTL (exactly 1/2 of the
    possible range of boustrophedon cases). Any implementation of a protocol
    or rendering system that's bidi conformant would be unable to provide
    boustrophedon support without violating that conformance. That makes
    widespread support even more difficult.

    Q: What should be done?

    A: People caring about ancient scripts should file a UTC paper requesting
    a) broadening of the existing exception to cover RTL scripts shown in
    LTR direction via overrides
    b) alternative: add a specification for boustrophedon (see below)
    c) work with W3C to support the necessary modes in HTML, CSS, etc.

    Q: What would be a reasonable Unicode specification for boustrophedon?

    A: It would have these elements
    a) boustrophedon is a permissible higher level protocol
    b) when active, details of mirroring can be overridden by the protocol
    that defines when and how boustrophedon is active
    c) when boustrophedon is active, normal bidi behavior applies, but
    relative to the direction of the current line (what was LTR is now
    downstream and what was RTL is now upstream). This preserves a definite
    meaning for the bidi format characters.

    In other words, true boustrophedon can be implemented consistently after
    bidi evaluation and reordering, by flipping every alternate line. The
    normal line breaking can be performed. The details of how to designate a
    run of text as boustrophedon and whether the first line is RTL or LTR,
    or which runs are exceptionally mirrored, would be outside the scope of
    the Unicode standard. (And could then be handled cleanly by HTML, CSS etc).

    Q: Do I expect anyone from that community to actually propose a
    technical specification?

    A: I'm not holding my breath.


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