owner of this attribute for an object instance is allowed to delete the object instance. Ownership of this attribute can be transferred at runtime using the above operations. Time Management Services The information exchange in an HLA federation takes place in real-time with immediate (Receive Order, RO) delivery of messages, unless HLA Time Management has been enabled. The purpose of HLA Time Management, described in chapter 8 of the HLA Interface Specification, is to guarantee causality and a correct and consistent exchange of time stamped messages (updates and interactions) in Time Stamp Order (TSO), no matter if the federation executes in real-time, faster-than-real-time, slower-than-real-time or as-fast-as-possible. Some important concepts in HLA Time Management are: Logical time: A time axis in HLA, starting at zero. Logical time is used for Time Management timestamps and operations. The logical time axis can be mapped to the scenario time of the federation. An example of such a mapping is to let zero represent the scenario time 8:00 of the 1-Jan-1066 and let an increment by one represent one second of the scenario. Lookahead: A time interval specifying the lowest time in the future for which a federate will produce messages. For a federate with a fixed time step, this is usually the length of the time step. Granted: A federate is granted (allowed to advance) to a particular logical time by the RTI, when all time-stamped messages up to that time have been delivered. The federate can then safely start calculating messages with a timestamp in the future. This timestamp may not be earlier than the granted time plus the federates lookahead. Advancing: When a federate has finished producing data for the granted time plus the lookahead, it may request to be advanced to a later time, which also means that it promises not to produce any more messages with a time stamp less than the requested time plus the lookahead. The federate is now in the advancing state. Time Regulating: A federate that sends time stamped events is considered Time Regulating since the time advance by other federates may be regulated by this. Time Constrained: A federate that receives time managed events is considered Time Constrained since the reception of time stamped messages, constrains its time advance. The main principles of HLA Time Management are that: Each time-regulating federate assigns a time stamp to messages (updates and interactions) when they are sent, indicating