The index of the actor source whose animations are used by each actor in a CrowdFX simulation, where 0 is the first actor added, 1 is the second, and so on. This attribute is set by Initialize Locomotion Data or Initialize Stadium Data.
This may be different than the mesh used by an actor, if Use Single Animation_Sources is checked in Initialize Locomotion Data or Initialize Stadium Data. If you want the index of the mesh instead, use Get Actor ID.
