Event (UML)
Template:Refimprove An event[1] in the Unified Modeling Language (UML) is "something that may occur at a specific instant in time".[1]
Events can, but do not necessarily, cause state transitions from one state to another in state machines[2] represented by state machine diagrams.
Consider "the case of two Transitions[3] originating from the same State,[2] triggered by the same event, but with different guards. If that event occurs and both guard conditions are true, then at most one of those Transitions can fire in a given run-to-completion step."[3]