[jltsiren]

The standard is based on the expectation that you should be able take a definition or a theorem out of its context and it should still make sense. The same symbols are often used for different things in different contexts, while concepts (even advanced ones) tend to remain unambiguous.

R is unambiguous if it's in blackboard bold, but otherwise it can mean almost anything. n is likely interpreted as a non-negative integer if left undefined, but you usually need to establish explicitly if it can be 0.