Determines the active source for a Hydraulic Study. Possible values for this property are -1 - wstNone: None (default), 0 - wstActiveSource: Active Source, 1 - wstScada: SCADA, 2 - wstOperator: Operator, 3 - wstCCLink: Control Center, 4 - wstBilling: Billing, 5 - wstCalculated: Calculated, or 6 - wstDatabase: Database. The selected source type must exist in the Discrete Measurement to be set as an input of a Hydraulic Study. If this property is set to 0 (zero, Active Source), it follows the configuration performed in the ActiveSource property. Users cannot select type 0 (zero, Active Source) if the ActiveSource property is set to 100 (output of a Topology Processor Hydraulic Study). In case the selected source is deleted, this property assumes a value of -1 (minus one, None).