Why incomplete subscript/superscript alphabet ?

[Jukka K. Korpela]

1.10.2016, 11:29, Khaled Hosny wrote:

> On Fri, Sep 30, 2016 at 07:31:58PM +0300, Jukka K. Korpela wrote:
[...]
 >> What I was pointing at was that when using
>> rich text or markup, it is complicated or impossible to have typographically
>> correct glyphs used (even when they exist), whereas the use of Unicode
>> codepoints for subscript or superscript characters may do that in a much
>> simpler way.
>
> That is not generally true.

It is generally true, but not without exceptions.

> In TeX you get true superscript glyphs by default.

I suppose you’re right, though I don’t know exactly how TeX implements 
superscripts. I suspect the fonts that TeX normally uses do not contain 
(many) superscript or subscript glyph variants, but TeX might actually 
map e.g. ^2 in math mode to a superscript glyph for 2 (identical with to 
the glyph for ²).

> On the web you can use font features in CSS to get them as
> well, provided that you are using a font that supports them.

This is a good example of my general statement. If you use the simple 
way in CSS, you use vertical-align set to sub or super together with a 
font-size setting. This is simple and “works”, but it does not use 
subscript or superscript glyphs but algorithmically operates on normal 
glyphs (and produces different results in different browsers etc.). The 
newer way, setting font features, is a) much less widely known, 2) much 
less supported in browsers, 3) requires extra settings to deal with 
browser-specific names of the relevant properties.

Yucca