From: Eric Muller (emuller@adobe.com)
Date: Thu Jul 24 2003 - 11:40:52 EDT
Alan Wood wrote:
>I think this leaves only one character in the old Symbol font that does not
>have a Unicode equivalent:
>
>RADICAL EXTENDER (decimal 96 in the Windows version)
>
>
When I prepared the proposal for U+23D0 ⏐ VERTICAL LINE EXTENSION, it
was indeed to ensure the complete representation of some other character
set in Unicode. My target was actually the PUA usage defined by Adobe,
which included what's needed for "the" Symbol font.
I did not consider perfect round tripping a necessity: it was enough for
me to allow the conversion of old data to Unicode, and to leave the old
world behind. Nor do I consider having a perfect handling of symbol
pieces in a Unicode only world a necessity: exchanging with somebody the
plain text "...U+23B2 ⎲ SUMMATION TOP U+23B3 ⎳ SUMMATION BOTTOM ... "
does not improve one bit our communication over exchanging "...U+2211 ∑
N-ARY SUMMATION..." Nor do I consider symbol pieces a good solution for
typesetting (*glyphs* for the symbol pieces may be a good thing for that
problem, but that requires more communication between a layout engine
and a font than a mapping from characters to glyphs).
For the RADICAL EXTENDER, I could not convince myself that such a
character was needed; U+23AF ⎯ HORIZONTAL LINE EXTENSION is a fine
character to use for that purpose. U+23D0 ⏐ VERTICAL LINE EXTENSION was
much easier to justify (i.e. nothing else made sense) and there was the
model of U+23AF ⎯ HORIZONTAL LINE EXTENSION to build on.
This represents only my opinion, and explains why I did not propose
RADICAL EXTENDER. It says nothing about how the UTC would react to such
a proposal.
Eric.
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