From: Asmus Freytag (email@example.com)
Date: Mon Feb 21 2005 - 18:02:45 CST
> > Is there actually any problem with using Variation Selectors as-is to
> > differentiate ...
Doug already answered about the fact that only standardized sequences are valid
and the only standardizer for sequences is the Unicode Consortium.
Beyond that, variation selectors have another limitation: their only
function is to identify variants - and that means variants with different
GLYPH, not variants with different *behavior*.
Variation selectors are designed to be ignorable for all processes that
don't deal in rendering, and, they are also ignorable for low-fidelity
rendering, i.e. rendering that does not support them (yes, I know, that's a
For distinctions in *sorting behavior*, a Combining Grapheme Joiner can
often be used - but it is not intended to result in differences in display.
The use of all of these special encoding crutches needs to be kept to a
minimum. We all know cases where using a variation selector is preferable
over adding a new character, since the differentiation is minute, not
universally applicable or both. However, most text processes have to be
designed to actively ignore them - and you have to be able to know, in
advance, for which process they can (and must) be ignored.
That means, you cannot arbitrarily use existing mechanisms to make
distinctions that matter to algorithms that were designed to ignore these
mechanisms. Therefore, for variation selectors, any non-glyphic
distinctions are completely out of the picture.
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