Re: script or block detection needed for Unicode fonts

Date: Thu Sep 26 2002 - 18:12:46 EDT

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    On 09/26/2002 02:54:55 PM "chuck clemens" wrote:

    >It appears as I mentioned in email to
    >Mark that Unicode fonts use block ranges. Can someone verify this?

    The TrueType font format allows a vendor to indicate which "Unicode ranges"
    a font supports. In Windows, there are APIs and data structures for making
    this information available to an app. The only problem is that the notion
    of "supports" is undefined: by what criteria does one decide whether a font
    "supports" a given range? Only if every character in that range is
    supported? Even if only one character in that range is supported? If >50%
    of the characters are supported? If all the characters from that range
    needed by some major language is supported? (If so, what major language,
    and how does one decide exactly what characters a language "needs"? Does
    English need the em dash? That depends upon one's purposes.)

    For details on Unicode ranges in TrueType fonts, see

    Note, BTW, that these are not used on the Mac (I don't know about other
    platforms). Also, there's a real possibility that the number of Unicode
    ranges that may eventually need to be supported by this mechanism in
    TrueType fonts will exceed the number of ranges that the format can
    accommodate (it's a bit vector of 128 bits, and 83 have been assigned
    values to cover up to Unicode 3.0).

    - Peter

    Peter Constable

    Non-Roman Script Initiative, SIL International
    7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
    Tel: +1 972 708 7485
    E-mail: <>

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