When multiple triggers are defined for a Transition, they are logically disjunctive, that is, if any of them are enabled, the Transition will be triggered. Source Unified Modeling Language 2.5.1
A Transition may own a set of Triggers, each of which specifies an Event whose occurrence, when dispatched, may trigger traversal of the Transition. A Transition trigger is said to be enabled if the dispatched Event occurrence matches its Event type. Source Unified Modeling Language 2.5.1
Transition::guard : Constraint [0..1] ... If the guard is true at that time, the Transition may be enabled, otherwise, it is disabled. Guards should be pure expressions without side effects. Guard expressions with side effects are ill formed. Source Unified Modeling Language 2.5.1
Transition::guard : Constraint [0..1] ... A guard is a Constraint that provides a fine-grained control over the firing of the Transition. The guard is evaluated when an Event occurrence is dispatched by the StateMachine. ... Source Unified Modeling Language 2.5.1
uml101 - StateMachines - NOTATION REFERENCE CARD Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo Section 01:03: UML Behavior: StateMachines quick start Slide kind UML StateMachine Diagram
An Event is the specification of some occurrence that may potentially trigger effects by an object. Source Unified Modeling Language 2.5.1
UML Event types for triggering Transitions This content has been marked as discussing an ADVANCED topic! Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo Section 01:03: UML Behavior: StateMachines quick start Slide kind UML Profile Diagram
A Trigger specifies a specific point at which an Event occurrence may trigger an effect in a Behavior. Source Unified Modeling Language 2.5.1
