Including a reference frame option for GetEntityState?

[ayushgnv]

https://github.com/ros-simulation/simulation_interfaces/blob/86d4cce610e12bfecc63bd1c76ca10147e1741db/msg/EntityState.msg#L3C1-L3C77

Given that this message type includes a reference frame, I suppose it is left up to the simulator to provide a frame that an Entity State is with respect to.

While some simulators may choose to always provide and input an EntityState in the world frame, others may have the option to provide the data in a different frame. For these cases, should GetEntityState have an option for a reference frame?
In Isaac Sim, for the most part, entities are treated as individual frames, in which case it might be beneficial to also provide an option for a reference entity?

If we dont include a reference frame option in the services, perhaps each simulator should notify somewhere (maybe in SimulationFeatures) what frame an EntityState will be provided in?