Re: Arabic and Adobe Flash

From: William J Poser (
Date: Mon Mar 26 2007 - 14:15:00 CST

  • Next message: William Kirtz: "RE: Arabic and Adobe Flash"

    Arabic characters fall into two classes. So-called "connectors"
    potentially link up both to the left and to the right. So-called
    "non-connectors" potentially link only to the preceding character,
    not to the following character. One says "potentially" because
    whether linkage actually takes place depends on whether there is
    a character to the left or right and what its own class is.

    The result is that connectors have four variants: (a) isolated;
    (b) left-linked; (c) right-linked; (d) doubly-linked.
    (In most descriptions of the writing system the misleading
    terms "initial", "medial", and "final" are used for "left-linked",
    "doubly-linked", and "right-linked".)
    Non-connectors have just two variants: (a) isolated; (b) right-linked;
    These variants are shown in any textbook of Arabic.
    In normal Unicode usage the rendering engine is supposed to take
    care of this, but if you need to compute it abstractly,
    the positional variants are also encoded in Unicode in the
    block "Arabic Presentation Forms B" U+FE70 through U+FEFF.
    If your rendering engine does not handle this, you will also
    need to take into account the fact that certain characters
    combine irregularly. The ligatures are to be found under
    "Arabic Presentation Forms A" U+FB50 through U+FDFF.


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