rror, the signal is sent to one of the instances. Output: no receiver process instance exists for the signal4 47 (e.g. the process instance stopped, the specified Pid is Null, or no path exists for the signal to the receiver process instance). If not configured to give an error, the signal is discarded. View-revealed: revealed statement is missing. View-revealed: variable revealed by several process instances. Import-Export of variable or procedure: errors similar to output (as exported values or procedures are translated into signal exchanges). Value out of range: for example, in a syntype, in an Array operator or in a String operator. 47 According to the configuration of the Simulator, this can be an error or not (see Edit > Configuration). 110 Validation of Communications Systems with SDL Variant not active: for example, in an ASN. 1 choice value. Optional ASN.1 field not assigned: attempt to access the field. Recursive call of procedure with states (this is an ObjectGeode restriction). Maximum number of SDL instructions in a transition exceeded: detects infinite loops in a transition. By default set to 1000. Can be changed by typing: define trans_events_limit'2500 Specific to ObjectGeode. Maximum number of recursive calls of SDL procedures (without states) exceeded: detects infinite calls. By default set to 100. Can be changed by typing: define call_depth_limit Specific to ObjectGeode. User specified error forced by the SDL error expression (for example, n := ERROR in a task symbol). Remark: division by zero is detected at C code level, not by the Simulator. 4.4.3 Dynamic errors not checked The following dynamic checks are not performed by Tau or ObjectGeode Simulators: Several answers to a decision match the decision expression value: the Simulator will arbi- trarily choose one of the existing paths. Overflow of Integer and Real values: this is checked at the C level if the actual C system performs such checks. Automatic Observation of Simulations 5.1 PRINCIPLES 5.1.1 Automatic checking of model properties I