Re: wrong ccc for 0602?

From: John Hudson (
Date: Thu Nov 27 2008 - 06:32:36 CST

  • Next message: Peter Zilahy Ingerman, PhD: "Re: Why people still want to encode precomposed letters"

    Hmm. This is a tricky matter, Arno, because the Arabic footnote sign is
    an enclosing mark that, in logical order, precedes one or more numerals
    will be positioned relative to the enclosing mark. Further, unlike
    combining marks, the enclosing marks are not usually zero-width. The
    traditional use you show would require not only a raised footnote sign
    but also corresponding raised numerals and, of course, that the
    combination of footnote sign and numeral(s) be zero-width so as not to
    affect the spacing of the text below.

    I definitely think it would be wise to distinguish between the existing
    footnote sign U+0602 and a new high, zero-width combining mark footnote
    sign. There isn't a standard mechanism within Unicode for translating
    baseline spacing characters into combining marks, and if one looks for
    parallels one sees, for instance, that the small combining mark letters
    like seen U+06DC are separately encoded and have, of course, different
    properties from the corresponding full-size, spacing letters.

    But once a high combining footnote mark is encoded, one still faces the
    issue of how to position numerals correctly relative to it. Positioning
    a single numeral relative to the mark would be fairly easy: a small,
    zero-width raised glyph could be contextually substituted for any
    numeral character. But if a footnote were to involve more than one
    numeral, matters would get very complicated, because the numeral glyphs
    would need to be spaced. This implies either chained contexts with
    zero-width numerals on different offsets, or kerning lookups between the
    mark-classified numerals that do not process base glyphs (I'm not sure
    if the latter would work: it needs testing).

    Then there is the question of how to handle a sequence in which a
    footnote mark plus dependent numeral(s) occurs in the text immediately
    adjacent to independent numerals, i.e. how does one distinguish between
    numerals that belong with the footnote mark and numerals that belong in
    the main text? Presumably one would require that a word space or other
    context-terminating glyph such as ZWNJ be inserted.

    John Hudson

    Tiro Typeworks
    Gulf Islands, BC
    You can't build a healthy democracy with people
    who believe in little green men from Venus.
                        -- Arthur C. Clark

    This archive was generated by hypermail 2.1.5 : Thu Nov 27 2008 - 06:35:30 CST