. A network element reports an event in the traffic system to its EM (EM1 here). EM1 analyzes the event. Depending on the type of event, it is either dealt with without notifying NM1, or stored in a local MO for reporting to NM1 later, or immediately reported to NM1. 2. NM1 may find that this event is related to an MO that is shared with MS2 (i.e., a "virtual MO"). It therefore tells its translation function for MS2 about the event. 5 Management and Traffic Systems 3. The translation function translates this information to an event of a particular virtual MO, which can be more or less complicated, if the vMO is not specified as a TMN-MO. The translation function then reports to its peer translation func- tion in MS2 that the particular event has happened, referring the vMO. 4. The receiving translation function in MS2 generates the vMO event towards its 5. This NM may just store the report for later use, order an EM in MS2 to perform some operation on an MS2-MO, or generate an alarm to be dealt with by an MS2 operator. If we include the TMN functions that adapt a TMN to different types of network elements, as well as interworking between a TMN and other management systems, we get the full picture of the TMN management plane/layer in its LSM representa- tion as shown in Fig. 5.14. Note that TMN calls an AF that can handle TMN-MOs and the TMN defined mpCP (called Q3) a "network element function" (NEF). MS3-WS (local) MS1 (TMN) MSTMN-WS Operator Operator function A relation that is defined by e.g. an AMLn model for the traffic system MS2-WS Managers Fig. 5.14 The complete picture TMN gives of the management layer LSM TMN defines this structure by giving names to the different control points. To be more precise: TMN does not define "control points," but "reference points," which is more a type of a network interface, since these points also include connectivity structures, such as the CMIS/CMIP protocol stack, according to Fig. 5.7. The mpCP and msCP of TMN are both referred to as Q3. 5.4 The Management System Interw