What is the current Unicode stance on subscripts and superscripts for mathematical use?

[Richard Wordingham]

On Tue, 23 Jun 2020 01:09:39 +0200
Marius Spix via Unicode <unicode at unicode.org> wrote:

> This can already be done by rich text. Unicode includes some
> superscript characters like ², ³ or ° (the degree sign is a
> superscript version of the white circle U+25CB) for compatibility
> with legacy character sets and phonetic transcriptions (in some
> languages the tone is important).

But still there can be annoying gaps.  Tai-Kadai is reconstructed to
have four tones, conventionally called A, B, C and D, and it is very
convenient to use the corresponding superscript letters to label the
tone on the syllables.  However, one of those capitals is missing, and
so in Wiktionary they have to make do with a superscript lower letter
for that one!  I don't think there's confidence in the
reconstruction of the original tones - and its possible that the tone
inducers, not the tones themselves, go back to the proto-language.

Richard.