@mirabilos @anon_opin @derickr TIL, there is actually a semantic slash character that pretty much does work as I describe, albeit without the needed for interspersing zero width joiners: https://unicodeplus.com/U+2044 It's just that as a result if you want to write a mixed fraction then you need a zero width non joiner (https://stackoverflow.com/questions/55033436/how-to-display-the-fraction-15-16-nicely-in-unicode#comment108667167_55034877). The biggest problem seems to be that its not universally supported though, hence why smooshing superscripts and subscripts still seems to be the best approach