I have seen in all controllers / hardware interfaces that support some kind of torque control only the hardware_interface::HW_IF_EFFORT so far and thought - okey that is what we are using for torques. I now stumbled upon hardware_interface::HW_IF_TORQUE.
I am wondering now: What is the right  type to use for an actuator that supports reading/commanding torques?
Is there some kind of rule/standard when to use what ?