This objectified relationship between a distribution flow element occurrence and one-to-many control element occurrences indicates that the control element(s) sense or control some aspect of the flow element. It is applied to IfcDistributionFlowElement and IfcDistributionControlElement. 

This relationship may be used to indicate an operational relationship such as an actuator operating a valve, damper, or switch. It may also be used to indicate a sensing relationship such as a sensor detecting conditions of fluid flow. This relationship implies a sensing or controlling relationship; if elements are merely connected without any control relationship, then IfcRelConnectsElements should be used.