Rejamming and calling rejams

Good evening,
in many texas holdem courses graphs (ranges) are shown which are called REJAMMING to be applied from different positions depending on the actual stack and depending on the position of Oppo performing a certain action.

For example with 30 BB if they are from CO with 99 1010 AQo and AQs.

So what would OPPO's action be before me? He went all in?

So REJAMMING should be understood as my ALL IN to a previous ALL IN from Oppo?

Finally, other graphs called CALLING REJAMS are shown.
What does it mean CALLING REJAMS. I mean what is the dynamic before my action?

Thank you