A «digital» variant may be used to explore possible or anticipated changes to a «physical»
PhysicalEntity
that is mapped by a unique «digital» 
@Entity
, but it not a direct part of the control loop of the «twin» DigitalTwin
. It may, however, be used by the control system as an idealised target for driving the «physical» PhysicalEntity
into a desired position (against which the unique «digital» 
@Entity
must then be synchronised).