Measurement Source used as active by the object. Possible values for this property are 1: SCADA, 2: Operator (default), 3: Control Center, 4: Billing, 5: Calculated, 6: Database, 100: Topological Processor, 101: Power Flow, 102: State Estimator, 103: Load Shedding, 104: Distribution Load Modelling, 105: Self-Healing, or 106: External Reader. The selected Source type must exist in the Measurement to be set as active. It is not possible to select types 100, 101, 102, 103 , 104, 105, or 106 (Electrical Study outputs) if the StudyInputSource property is set to 0 (ActiveSource). In case the selected Source is deleted, this property assumes a value of 2 (Operator).