FPDAM5 : Egyptian hieroglyphs properties (was: Fish)

From: Philippe Verdy (verdy_p@wanadoo.fr)
Date: Sat Sep 29 2007 - 18:25:43 CDT

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    Michael Everson wrote:
    > At 11:34 -0500 2007-09-29, vunzndi@vfemail.net wrote:
    > >So before this thread is stopped. Who is going to write the proposal
    > >to encode <><?
    >
    > See U+1319F in FPDAM5

    If I look at the current FPDAM5 documents, I can see that it adds a new
    large block of Eyptian hieroglyphs. But, independently of the encoding by
    ISO of these characters, there remains the question of their properties that
    will affect the way they are rendered (or interpreted).

    I can't see those details in the referenced documents N3237, L2/07-097 and
    N3345... But these details will be needed for inclusion in the Unicode
    standard. Did you start a discussion somewhere about their intended
    character properties and the content of the future presentation chapter in
    the amended Unicode standard?

    The main questions about the proposed hieroglyphs are:

    (1) About their directionality:

    - (1.1) What will be their default directionality: left to right, top to
    bottom, other? Inherited from the text before them, or from a leading
    direction override format control? Will new direction overrides be
    introduced to support the vertical layout if the default direction is
    horizontal? In horizontal boustrophedon style, will it support the inversed
    ductus on even lines (i.e. with mirrored glyphs, like for Old Greek rendered
    in boustrophedon style) or will the ductus be kept constant (non mirrored
    glyphs)?

    - (1.2) How can a text encode a change of direction explicitly (if a single
    leading control format does not encode the boustrophedon or spiral style
    implicitly for the rest of the text): with an explicit format control
    inserted everywhere a direction break occurs or after each explicit line
    break control?

    - (1.2) Which characters should be mirrored, or rotated when displayed in
    boustrophedon style or vertically? Can this implicit reorientation be
    overridden for specific characters or spans of characters?

    - (1.3) How will line breaks work? Does it preserve the directionality or
    does it swap it?

    - (1.6) How will the BiDi algorithm be affected?

    (2) About the cartouches:

    - (2.1) Characters are added to encode the beginning or end of a cartouche
    (with a representative glyph showing the left or right part of the
    cartouche) but no combining character is added to modify the enclosed
    hieroglyphs. Does this mean that the upper or lower parts of the cartouche
    is inherited from the previous hieroglyph, starting by the character
    encoding the beginning of the cartouche?

    - (2.2) Is the presence of cartouches affecting the position of candidate
    line breaks (if the text is not rendered in a boustrophedon style, either
    horizontally or vertically, or in a spiral style: in both styles, the line
    breaks do not affect seriously the way in which the cartouches are rendered,
    given that they can run continuously, because the whole text looks
    effectively like a single zigzagging line, where the text baseline is not
    necessarily oriented in the same direction as the glyph baseline when the
    glyph orientation is kept)?

    Also, it seems that wordbreaks are not a difficulty for hieroglyphs (but
    there may be exceptions with special symbols appearing around hieroglyphs,
    notably the cartouche delimiters (acting like surrounding punctuations, but
    also possibly prohibiting some line breaks in the middle if the text
    direction is kept constant between two lines), or specific punctuation
    signs, or hieroglyphic numbers and date symbols.

    For scientific documents discussing the hieroglyphs script, it may be
    acceptable to use the convenient unidirectional style (as used in Latin or
    Arabic), but for rendering complete hieroglyph texts, supporting vertical
    layouts or boustrophedon or spiral layout will be needed (additional
    constraints for better rendering will soon appear like the need for full
    line justification in boustrophedon or spiral styles, but this is a much
    less critical issue).

    Also for the spiral layout (if someone wants it), the rendering of a contour
    outline delimiting the direction for reading may be needed (to help
    readers), but this may be addressed by style without affecting the encoding
    itself, as this contour may or may not be present. This contour outline
    should not be confused with cartouches that are part of the encoded text and
    have their own glyph.



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