Add options for math superscript and subscript commands

[texno3]

May I ask if it is possible to add options for math superscript and subscript commands, such as math-subscript-command and math-superscript-command, whose defaults are \sb and \sp, respectively, so that other commands can be used to set the format of the superscripts and subscripts of the math , such as the \sub and \super commands of my macro package spbmark.

[josephwright]

The model for siunitx to generate 'properly formed' (La)TeX math mode material as an intermediate to then typesetting either in math mode (directly) or in text mode (using appropriate substitutions). For sub/superscripts, that means _ and ^, which in text mode map to \textsuperscript/\textsubscript. If a document author or a package needs to redirect the results, that should apply generally, not just to units. For math mode, I'd expect to see that done using \mathcode or in text mode by redefining the \text...script commands.