How is ego_vehicle location choosen?

[PriestOfAdanos]

Hi!
I am new to carla and would like to clarify one thing that bothers me:

Where is ego_vehicle /tf located?
Specifically, I would like to know if it is placed:
In relation to some bone
OR
In relation to some average/mean mass point

And where it is placed on the vehicle(directly under it on the floor, on the bottom("belly":) of the vehicle or someplace else

I know this is a rather basic question but I want to place my sensors as precisely as possible and this seems relevant.
If this is possible I would love to see a code snippet that implements it.

Cheers!