Thank you for the link JSH, now my written pidgin German attempts will look so much better with all those umlauts, and ßs

Superscript minus in Unicode is U+207B.

I have a vague recollection that there is a way to type Unicode hex codes into MS Windows but sorry, I really can't remember the details. Might help find it in one of those character applets, or whatever.

On Ubuntu Gnome you can type it by pressing and holding the control and shift keys, typing 'u207b' then releasing the control and shift keys. Similar for all other Unicode characters, of course. Superscripts 1, 2 and 3 are odd for historical reasons, all the other super- and subscripts follow a tidy pattern.

U+2070 ⁰ U+2080 ₀
U+00B9 ¹ U+2081 ₁
U+00B2 ² U+2082 ₂
U+00B3 ³ U+2083 ₃
U+2074 ⁴ U+2084 ₄
...
U+2079 ⁹ U+2089 ₉
U+207A ⁺ U+208A ₊
U+207B ⁻ U+208B ₋
U+207C ⁼ U+208C ⁼
U+207D ⁽ U+208D ₍
U+207E ⁾ U+208E ₎
U+207F ⁿ

On Ubuntu Gnome you can get quite a few interesting characters with the otherwise little used alt gr key. Alt gr 1, 2 and 3 give the superscript digits easily. Alt gr m gives Mu: µ (U+00B5). Alt gr . gives middle dot: · (U+00B7). Another useful character is U+00B0 degree symbol: ° for which, regrettably, I have not found an alt-gr combination. Irritatingly (very slightly) many people use the character U+00BA (º Masculine Ordinal Indicator) for this which comes out with a little underline in many fonts.

Ed - people use U+00BA (º Masculine Ordinal Indicator) because it's on <altgr+shift+m> and looks enough like degree that it's likely to get use if found first. The proper degree symbol is on <altgr>+<shift>+<0> (Zero, not Oh).

All those runes Ed mention work approximately the same on Debian too (although I haven't got superscript 2 and 3 on the same keys for some reason). There are also dead-key options which let you add an umlaut to other chars: ëöäï which you get with <altgr>+<"> followed by the letter of interest <a>,<o>,<u> etc. And similarly for <'> to get acute accents, <~> to get tildes, and presumably something to get graves, but I can't find the key.

Here is the full gen: https://help.ubuntu.com/community/ComposeKey with all of the above methods, list of keys, etc.