a particular object class, either with a reserved name or an automatically generated name. DiscoverObjectInstance that is used by the RTI to notify federates subscribing to particular object class that a new object instance has been registered. DeleteObjectInstance that is used to delete an object instance RemoveObjectInstances that is used by the RTI to notify federates that an object instance has been removed Attributes: UpdateAttributeValues that is used to provide updated attribute values for an object instance ReflectAttributeValues that is used by the RTI to notify federates subscribing to particular attributes of updated values. Interactions: SendInteraction that is used to send an interaction of a particular interaction class, including parameter values. ReceiveInteraction that is used by the RTI to deliver an interaction, including parameter values, to federates subscribing to a particular interaction class Ownership Management Services The purpose of Ownership Management services, described in chapter 7 of the HLA Interface Specification, is to dynamically manage what federate that simulates what aspect of an object instance. In HLA, only one federate is allowed to update a given attribute of a given object instance. That federate is considered the owner of the attribute. A federate that registers a new object instance will automatically be the owner of all attributes it publishes. In some cases, attributes of an object instance may become unowned, i.e. not owned by any federate. Ownership management provides services for transferring ownership of one or several attributes at runtime, which can include a federate Divesting the attribute and another federate Acquiring the attribute. There are two main patterns: “pull” that are initiated by the acquiring federate and “push” that are initiated by the divesting federate. Key services for initiating “pull” ownership are: AttributeOwnershipAcquisitionIfAvailable which is used by a federate that wishes to acquire ownership of unowned attributes. AttributeOwnershipAcquisition which is used by a federate that wishes to request ownership of a potentially owned attribute Key services for initiating “push” ownership are: AttributeOwnershipDivestitureIfWanted which is used by a federate that wishes to divest attributes only if there is some other federate that is standing by to acquire ownership of these attributes. NegotiatedAttributeOwnershipDivestiture, which is similar but may also cause the RTI to try to find a new owner. UnconditionalAttributeOwnershipDivestiture, which is used by a federate that wishes to give up ownership, even if no new owner can be found. All object instances have a predefined attribute called HLAPrivilegeToDeleteObject. Only the