Q:

Notation for planes

This might be a dumb question, but I was wondering what symbols/letters are used when labelling planes in 3D. For example, lines are represented using $l$, $m$, $n$, etc... I've seen people using $\pi$ for planes, but are there any others?

A:

Unfortunately, there is no standards... most of the time. Different mathematicians use different notations. In any case, people often use $p$, $q$, and $r$.

