Is it possible to define a macro which (in math mode) typesets normal math and subscripts in different fonts?
Concretely, I am interested in typesetting the math in roman and the subscripts in italic, such that
would result in
In response to an answer, let me clarify that the hope would be that this works on equal footing for a general parameter string (at least as long as it only includes characters and alphanumerical subscripts), such as $A_pB_r$, $ABC_s$, $A_xBC_y$, and so further. Clearly, this can be broken down to individual letters with & without subscripts, but this would make the involved expressions extremely cumbersome and lengthy to type up.