Re: Unicode and math symbols

["Martin J. Duerst" <mduerst@ifi.unizh.ch>]

On Fri, 28 Feb 1997, Berthold K.P. Horn wrote:

> 
>    Berthold
> 
>    Just a few questions to you to clarify matters:
> 
>    Does this dependence of OSs on the Unicode standard mean that whenever
>    Unicode changes, everyone needs a new version of the OS or just new
>    font-files, or what?
> 
> The support for all this right now is still rather poor, actually.
> 
> (1) For example, the Microsoft NT font installer has a fixed table
> of glyph name to UNICODE mappings (complete with typos like
> aroowleft, hungerumlaunt, traglf).

Microsoft wrongly uses Unicode as a kind of glyph repertoire,
and can get away with it as long as they don't deal with
Indian scripts.

The correct solution is to not have the system do the conversion
between character codepoints and glyph indices, but to leave that
to the font (which should know best). Quickdraw GX (from Apple) and
TrueType open are approaches to this, although I would prefer
it if the knowledge of the font about the mapping were available
as methods (in the OO sense) and not just as tables.


> (3) The coverage of this table is limited, mostly WGL4 (which covers
> about 662 glyphs, including all the Latin alphabets, Greek, Cyrillic)
> (And in the current implementation it actually covers less).

Well, for the bulk of Unicode, CJK, names are a silly idea anyway.


>    > BUT: what they consider not to be in UNICODE is not accessible.
>    by "not in" do you mean that if a slot is empty in what that OS thinks
>    is the Unicode encoding then I cannot access a glyph in that slot in any
>    font?
> 
>    So how does one use Poetica on NT?

The main problem with the approach I proposed above (that the font
knows how to do the mapping) is that you have to think about ways
to bring in the preferences of the application. Poetical is a
particular example, but still lots of decisions could be made
by the font itself depending on character combinations.


>    And, if anyone knows, does plan 9 also have font-encodings hard-wired
>    like this?

Plan 9 is in a very early stage as with respect to character -> glyph
mapping and other kinds of font support such as outline fonts. It's
just not their area of interest/expertise, at least not currently.


Regards,	Martin.