Event
An Event represents a meaningful occurrence in the modeled world or operational domain.
Specification-sourced: quoted from the governing specification, pending the applicable specification-owner approvals. The specification controls.
In RSMOne's words
Harvest completion, a shipment arriving at the mill or a certification expiring are Events in the modeled world. A domain Event is not the same object as the infrastructure message that announces a change in system state, even though both are called events.