Hi SG16 :-)

At the last meeting about units, I said that we do not have to decide on
any specific Unicode symbols for now, as the systems of units are the
subject of the next papers. It turns out I was wrong :-(

We need a few Unicode characters for the first proposal. Those are:

Name Symbol C++ code Portable alternative
Superscript Zero ⁰ u8"\u2070" "0"
Superscript One ¹ u8"\u00b9" "1"
Superscript Two ² u8"\u00b2" "2"
Superscript Three ³ u8"\u00b3" "3"
Superscript Four ⁴ u8"\u2074" "4"
Superscript Five ⁵ u8"\u2075" "5"
Superscript Six ⁶ u8"\u2076" "6"
Superscript Seven ⁷ u8"\u2077" "7"
Superscript Eight ⁸ u8"\u2078" "8"
Superscript Nine ⁹ u8"\u2079" "9"
Superscript Minus ⁻ u8"\u207b" "-"
Multiplication Sign × u8"\u00d7" "x"
Mathematical Italic Small Pi 𝜋 u8"\U0001D70B" "pi"
Per Mille Sign ‰ u8"\u2030" "%o"
Dot Operator ⋅ u8"\u22C5" <none>*
* This option is valid only for UTF-8 encoding. Otherwise, we propose to
throw an exception during format string processing.

1. Did I choose the correct Unicode symbols for those?
2. Is the C++ spelling correct? Should we spell them in the spec with '\u',
'\U', or maybe some other way?
3. Are the portable alternatives fine (especially "%o" might be
controversial above)?
4. Is there a better way to spell `inline constexpr auto 𝜋 = pi;` to be
explicit about the specific Unicode symbol used for the identifier?

Best

Mat