From: Asmus Freytag (email@example.com)
Date: Fri Aug 14 2009 - 12:39:15 CDT
I think Julian makes a good point. There has been a gap in the
Now that the role of variation selectors has become clearer and more
widespread (IVD), it makes sense to identify places where it belongs,
but hasn't been used. In both IPA and mathematical usage, there are
characters which must not be rendered with some of the otherwise normal
choices of glyphs, lest the notation become ambiguous. It's the "a" with
handle at code point 0041 for IPA; for math if would be ensuring the
looped form of "phi" at 03C5, so that it contrasts to 03D6, etc.
So far, the official recommendation has simply been "don't use a font
that's unsuitable for IPA (resp. unsuitable for math)".
This requirement is only known to the author of the text, so such text
can only be created in those rich text formats where control over the
font choice rests with the author of the document. (Which, notoriously,
is not the fact for HTML, a rich text format where font substitution
somewhere between author and reader is more than likely).
With the use of variation selectors, in contrast, it would be possible
to encode the requirement for the restricted range of glyphic variation
in the text. If a font supported the variation sequence, it would be
used, otherwise the software would be able to substitute a font that
supported it, or was otherwise known to provide a suitable glyph.
For mathematics, the problem is perhaps less acute, since it's already
necessary for software (or document formats) to split the text into math
and non-math runs of text in many instances, because the formatting and
layout rules differ. But wherever individual variables are cited in the
accompanying text such identification might break down, and variation
selectors might still be useful.
Furthermore, the use of variation selectors would enable a larger set of
fonts to serve mixed use, wherever certain notations have arbitrary
glyph requirements that only partially overlap with the natural glyph
range for a given character. (There'd still be enough fonts that remain
unsuitable for notational purposes, but there'd be a larger choice of
"safe" plaintext fonts).
By adding a few variation selectors, the encoding model could be made
complete. Alternate character codes would cpntinue exist whenever
symbols/entities are used in contrast with each other. Variation
sequences would be used when the glyph-range is restricted for
notational purposes. By adding a variation sequence, the piece of
semantic information that a character is intended for notational purpose
and thus requires a restricted glyph range can be made explicit in the
(plain-)text and no longer has to be implied by styling information
On 8/14/2009 8:22 AM, Julian Bradfield wrote:
> Don't forget there's chi, as well as beta and theta.
> As a hard-core IPAist, who type my phonological papers in a text
> editor using a single Unicode font (the necessary font switches for
> print being LaTeX markup), I would naturally prefer to have separate
> characters for IPA chi, beta, theta.
> However, I do have some qualms about this: why do I not also need a
> separate ipa "a" - I might be using a font in which the normal "a" is
> actually ɑ-shaped! Indeed, really I would like separate codepoints for
> all IPA letters - but we know that would fail dismally in practice,
> even had it been implemented from the start.
> Given the situation as it is, I support the idea of variation selectors.
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