This OPC UA Property, of DataType BACnetDeviceObjectPropertyReference, represents the BACnet property Controlled_Variable_Reference. The BACnetDeviceObjectProperty Reference DataType is defined in 10.5.9.
This property identifies the property used to set the Controlled_Variable_Value property of the Loop object. Normally this is the Present_Value of an Analog Input object that is used to measure a process variable (for example, temperature) but it could also be another object. See the BACnet specification for additional examples.