Signals between officials?

[Lotto]

Good morning, all. I was wondering if there was a list somewhere of signals that officials use to communicate with each other. We go over these in pregames all the time -- something to remind each other that the next foul is in the bonus, or that the shot clock is low during an inbounds play, etc. What signals do you use? It would be great to compile a list to share around if one doesn't already exist.