I think I intentionally didn't do this specifically because of things like a^zeta(x). It's not all all clear to me which should have higher precedence. For fractions it's different because there is no sensible other interpretation.

Yeah, I considered that too. Here was my rationale:

• It's how latex works: a^\abs{b}_\sqrt{c}
• For non-idents (e.g. log_2(x)), we can tell you're not making a function call with certainty, so we should just let your write that.
• For cases like a^abs(b)_sqrt(c), it is very obvious that the user wanted to call the function, so we should treat it like that.
• For cases like a^zeta(x), it's unclear what should happen. Thus, my thinking was that we cater towards the obvious cases and let those determine the behavior of this ill defined case. So it will be treated as a function which can easily be circumvented by adding a space if that's not what you meant.

You were right, all it required was changing the math_op precedence!

Thanks!

Side note but a_\sqrt{b} is an "implementation artifact that happens to work", it's not a supported LaTeX syntax at all, and "tiny unrelated changes" might break it. In fact the only supported syntax is a^{2} instead of a^2, but on trivial detail like this one people are more likely to accept it...