This is a draft proposal to encode additional subscript and superscript characters in future versions of Unicode, motivated mainly by computer programming for technical applications.
Many programming languages (C#, Go, Java, Julia, Python, Rust, Swift, etc.) now
allow identifiers to use a wide array of Unicode characters, which enables
programs in mathematical fields to use notations that closely hew
to the original mathematical notations. e.g. one can now have variable names
like x̂ or αₓ. Unfortunately, this opportunity is hampered by
a lack of subscript and superscript characters in Unicode 9. (Most
famously, there are superscript characters for every lowercase Latin
letter except q.)
We believe that, given the recent explosion of Unicode support in programming languages (and editors), the time is ripe to propose better support for mathematical subscripts/superscripts in Unicode.
Our proposal is to add combining characters, mathematical subscript and mathematical superscript, that indicate that the previous glyph (a character + combining characters) should be rendered in sub/superscript form. Fonts can then implement these characters as "ligatures" for selected characters, so that e.g. an "A" followed by "mathematical subscript" would render as a subscript "A".
First, we welcome comments on this proposal (in the form of issues or pull requests): corrections, references to notable sources/applications, and technical comments.
Second, we suspect that it will be easier to get the Unicode Consortium to take us seriously if prominent authors, organizations, free/open-source projects, and companies can sign on to this proposal (as co-authors or endorsers).
Third, it will greatly strengthen the proposal if we can commit to providing draft fonts or (for new combining characters) the necessary improvements to text-rendering software, so experts in those areas are welcome.