When I fly near my local airport (
KSSF) in San Antonio, there's a designated South Practice Area and North Practice Area. ATC knows where they are and all the flight schools at the airport seem to have a common idea of their boundaries.
However, they aren't marked anywhere on charts or supplements and I can't seem to find any information online. I was wondering how these are communicated between different entities (control towers, ARTCCs, flight schools) - are they standardized at all? Is there anywhere I can find information?