Math spacing
From ConTeXt wiki
TeX handles math spacing by breaking a formula into parts, and assigning each of those parts a role such as 'Ord' (a variable or number) or 'Rel' (equality, larger than, et cetera). For each combination of roles, it then looks up the spacing appropriate between them in a table. These are the roles:
Ord | e.g. 4 or a or x^{2} |
Op | Unary operators such as sin or ln. |
Bin | Binary operators such as '+' |
Rel | Relationships such as '=' or '>' or '\implies' |
Open | open brackets of any kind |
Close | closing brackets of any kind |
Punct | Punctuation: digit separators like '.' or ','. |
Inner | Fractions are inner. What else is inner? |
To set up e.g. the spacing between ordinal items, do as follows^{[since 2012]}:
\startsetups math:morespacing \ordordspacing\textstyle 1mu plus .5mu minus .25mu\relax \stopsetups
\setupmathematics [setups=math:morespacing]