Date: Mon Feb 21 2005 - 18:44:40 CST
1. Then it sound like:
- Serbian Cyrillic Small "t"
- Coptic letterforms for Greek letter codepoints
- complete Archaic Greek and Asia Minor scripts aligned to Greek letter codepoints
are exactly what the Variation Selectors were designed for. There are no
issues other than a smart font substituting an alternate glyph. They can
default in a "low-fidelity" rendering to the primary codepoint glyphs. I would
welcome individual codepoints for them, but Unicode has already decided
otherwise. There is a clear need to be able to access the glyphs somehow, on a
device which has only one general Unicode font installed.
2. I don't know much about:
- alternate CJK ideographs and syllabographs
But I imagine some or all of them would fit the criteria as well.
3. German Sharp S which I mention, is probably too complicated under the
present Variation Selector definition, and will have to go down to my second
category with combining marks.
4. So, that leaves me a little mystified why a variation selector isn't
already in use for the notorious Serbian "t". Seems a lot more practical than
switching language identifiers every word in an HTML Russian-Serbian dictionary.
5. As to functions with combining marks, much of my original post discusses
the likely need for a new class of differentiating codepoints, other than
Variation Selectors, to handle that. In some cases the CGJ (or ZWJ) might be
usable, though I am already finding an essential problem with that for umlaut
vs. diaeresis (which you are all just dying to hear about -- and which
urgently needs to be solved).
Asmus Freytag wrote:
> > > 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
> bit circular).
> 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.
This archive was generated by hypermail 2.1.5 : Mon Feb 21 2005 - 18:31:16 CST