has explored all the states of the SDL model reachable in the current test configuration (input ports limited to 1 etc.). 7.3.6.2 Analyze the nonexecuted SDL statements After performing bit-state simulation, we must inspect the parts of the SDL model never exe- cuted. We see in the results displayed: Symbol coverage : 93.77 Lets see exactly where the 6.23% never-executed symbols are. A. In the Validator, select Commands > Show Coverage Viewer. The coverage viewer window appears as in Figure 7.34. If you double-click on the symbols marked with a zero, the SDL Editor opens the corresponding diagram and selects the symbol. The two uncovered symbols under process dispatch correspond to the reception of a v76frame containing a DM. The four symbols under process DLC correspond to two ELSE answers, supposed to never occur, and to the reception of a v76frame containing a DM under state waitUA shown in Figure 7.35. These two uncovered receptions of v76frame containing a DM cannot happen in our sim- ulation, because signal L_ReleaseReq is never transmitted to side B (because the channel dis has been disabled in file sig_defs.com), but only to side A. Therefore, a connection established by A cannot be refused by B: the scenario shown in Figure 7.36 cannot happen. The MSC in Figure 7.36 shows the parts missing in the SDL model to refuse a connection: first, in process dispatch under state waitEstabResp the input of L_ReleaseReq is missing: Figure 7.37 shows this input added, followed by the transmission of DM. Second, when DM is received in dispatch, the answer DM is missing: Figure 7.38 shows this answer added, passing the DM to process DLC. Now, as process DLC can receive DM, the symbols shown in Figure 7.34 should be covered by the simulation. B. Exit from the Validator (answering No to the question). C. In Windows (or Unix), make a copy of the file dispatch.spr into dispatch_v8.spr. D. Add the missing parts in process dispatch, as depicted in Figures 7.37 and 7.38. E. Save the SDL model. Exhaustive Simulation 213 SDL Cov