Grade Appeals

I’m just looking for a sense of the lay of the land. Readers from all sorts of institutions are invited to answer.

How does your college handle grade appeals by students?

Can appeals address judgments, or only errors of calculation? Can grades be changed if the professor objects? Who gets to make the call? Does the system seem to work?

If you’d rather answer privately than comment publicly, I’m at deandad (at) gmail (dot) com.

Thanks!