s are defined in [MSC96]. MSC test1ops start cnx1h MSC reference ready condition data_a2b data_b2a connection point Figure 5.31 HMSCs symbols accepted by the Validator 5.2.5.6 Time in MSCs When simulating with an MSC or HMSC, the time is considered global to all the instances present in an MSC. For example, if you load the MSC shown in Figure 5.32 into the Validator 132 Validation of Communications Systems with SDL MSC time1 proc1 proc2 proc3 proc4 proc1_1 proc2_1 proc3_1 proc4_1 Figure 5.32 MSC with four instances and simulate the SDL sequence sA, sC and sB, you get a violation report, because sB was expected before sC. 5.2.6 Simulate with observer processes You will add an observer process to detect if the variable uData in process dispatch in block DLCa contains 55. A. In Windows (or Unix), make a copy of the file v76test.ssy into v76test_obs.ssy (to keep a version of the SDL system without observer). B. In the Organizer, select V76test, choose Edit > Connect, choose To an existing file, press the folder-shaped icon and connect to the file v76test_obs.ssy. C. In the Organizer, press the save button. D. In the SDL Editor, check that you are editing the file v76test_obs.ssy, and add a block reference named obs, as shown in Figure 5.33. E. Double-click on the block obs, confirm the two windows, and add a text symbol containing the include statement shown in Figure 5.34, necessary to call observation operators. Type exactly the same words, respecting the case, and do not add spaces. F. In the block obs, create a process reference named obs1. Don't forget to press the save button in the Organizer from time to time. The Organizer should now look like Figure 5.35. G. In the SDL Editor, double-click the process reference obs1: after two confirmations, the content of process obs1 is displayed. H. Copy the observer represented in Figure 5.36: in the start transition, displ is filled with the Pid of the first instance of process dispatch, inside block DLCa. From state testing, if the variable uData in process dispatch co