Una referencia a otro rigidbody al que esta articulación se conecta.
Si no está definido, entonces la articulación conecta el objeto a un punto fijo en el espacio del mundo.
Unity does not support connecting a joint to a Rigidbody in a different Scene that is using a local physics Scene. If a joint is connected to a Rigidbody, and then that Rigidbody is moved to a Scene that uses LocalPhysicsMode.Physics3D, then the joint is automatically disconnected from the Rigidbody.
See Also: Scene and LocalPhysicsMode.