Re: uppercase and lowercase numbers

From: Adam Twardoch (list.adam@twardoch.com)
Date: Fri Feb 06 2009 - 14:38:06 CST

  • Next message: John (Eljay) Love-Jensen: "RE: uppercase and lowercase numbers"

    Eljay,

    in the common understanding, upper- and lowercase numbers do not convey
    any semantic difference, there is only stylistic (presentational)
    difference. Therefore, they share the same codepoints, and the actual
    glyph variants are selected using a layout technology such as OpenType
    Layout (or AAT or Graphite).

    Typically, when using OpenType Layout and OpenType fonts, the glyphs for
    uppercase numbers serve as default glyph representation for the number
    codepoints, i.e. those glyphs have the codepoints assigned directly in
    the font's "cmap" table, while the lowercase numbers are selected by
    replacing those glyphs with the appropriate lowercase number glyph,
    which is done using the "onum" (oldstyle numerals) OpenType Layout
    feature in the font's "GSUB" table.

    In some fonts (e.g. Microsoft's Constantia), the lowercase glyphs are
    default glyph representation of the number codepoints and are encoded
    directly. In this case, the uppercase numbers would be selected using
    the OpenType Layout feature "lnum" (lining numerals), and also, in
    addition, through the "case" (case-sensitive forms) OpenType Layout
    feature.

    A.

    John (Eljay) Love-Jensen wrote:
    > Hi everyone,
    >
    > Are U+00030 through U+00039 uppercase or lowercase numbers? Or neither / unspecified?
    >
    > If uppercase, are there lowercase number codepoints?
    >
    > If lowercase, are there uppercase number codepoints?
    >
    > If neither / unspecified, are there other ranges intended for uppercase number and lowercase number codepoints? Even if it is the private use area.
    >
    > I gave the glyphs in the Unicode specification a browse, and did not see whether-or-not there were such ranges. Maybe I missed it. Hence, this message.
    >
    > Examples of uppercase and lowercase numbers:
    > http://www.adobe.com/type/topics/info5.html
    >
    > Thanks,
    > --Eljay
    >
    >
    >
    > 

    -- 
Adam Twardoch
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