RE: Generic base characters

From: James Kass (
Date: Wed Jul 18 2007 - 00:25:12 CDT

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    > 1) There is absolutely no requrement, from Unicode's side, to include a dotted
    > circle in a font.
    > 2) As I've mentioned (quite often by now), Unicode does NOT require inserting
    > dotted circles like that.
    > ...

    Indeed. On some sytems, though, if a font does not include
    a glyph for the dotted circle character, the combining mark
    will be displayed on the "missing glyph" instead.

    Quoting from the Microsoft OpenType Indic specifications at:

    “For the fallback mechanism to work properly, an Indic OTL
    font should contain a glyph for the dotted circle (U+25CC).”

    (Note that the page appears to have been around since 2001.)

    Sinnathurai Srivas' observation about Indic fonts generally
    including a glyph for the dotted circle character is true
    because programmers tend to build OpenType Indic software
    according to the Indic OpenType specifications.

    > ...
    > However, it does not rule it out either, as it should do (at some appropriate level).
    > (There is no dotted circle in the character string below, but some systems, ill-advicedly,
    > insert one
    > during display.)

    (Well, some system between us apparently inserted line feed characters
    into your *text*.)

    To forbid an operating system from inserting some kind of a
    control picture in the display to highlight that which is “invalid”
    would be just about as bad as forbidding an operating system from
    inserting a line-feed (character) into the *display* where needed. (Of course, line-wrap can usually be turned off by people who like scrolling sideways.)

    The trick is to make sure that the font-engine handles all
    reasonable user expectations as “valid” ones. There's a learning
    curve involved, as there is with most nascent endeavors.

    Best regards,

    James Kass

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