 second occurrence of the sequence sA, sB, sC is also detected as a success. When using search, the simulator performs a loopback in the observer MSC to detect several occurrences of the MSC behavior in the simulation. If we set the simulation attribute of the MSC observer to verify: the first occurrence of the sequence sA, sB, sC is detected as a success; the two consecutive sA, sA provoke an error; then, at the end of the last sequence sA, sB, sC, no other success is detected. 16 Do not confuse this MSC attribute with the name of the command used to run the exhaustive simulation. 17 In previous versions of ObjectGeode, verify MSCs only detected errors. 156 Validation of Communications Systems with SDL MSC Simulation Properties Unexpected signals: Search Verify Complete test purpose Test purpose complete for inputs Partial test purpose Global Local Apply Cancel Figure 5.68 The Editor window showing the MSC simulation properties Observer MSC Simulation trace test_seq seq_sim inst_proc1 search verify inst_1 proc1 proc1 SUCCESS SUCCESS ERROR SUCCESS Figure 5.69 Simulation results with the basic MSC test_seq Figure 5.70 shows the simulation results with the hierarchical observer MSC test_loop. The observer is the same as in Figure 5.69 (it expects output of sA, sB and sC), but it has been inserted under the repeat operator test_loop: the sequence sA, sB and sC can now occur, and be repeated 0 to n times. Automatic Observation of Simulations 157 Observer MSC Simulation trace search verify seq_sim inst_proc1 test_loop proc1 SUCCESS SUCCESS test_2 SUCCESS test_2 inst_1 proc1 ERROR Figure 5.70 Simulation results with the hierarchical MSC test_loop If we set the simulation attribute of the MSC observer to search: the first output of signal sA is detected as a success: this corresponds to the execution of the repeat operator 0 times; then, no other success is observed. It means that the repeat operator must be avoided on top of a hierarchy of MSCs when using search; but the repeat is not necessary here because the simulat