From: John Hudson (john@tiro.ca)
Date: Thu Nov 27 2008 - 06:32:36 CST
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 www.tiro.com Gulf Islands, BC tiro@tiro.com 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