Triggers cause state transitions or static reactions. Events, conditions or a combination of both can be triggers. Sources for internally generated events are actions, timeouts or sensors for detecting the status of states, activities, conditions and data items. Events may also be a compound set of other events and conditions. Events are represented as a alphanumeric labels on transition lines or in the On field in state definitions.
Conditions can be edge or level-sensitive.
Actions Actions are instantaneous operations and are performed as a result of some trigger. Changing the value of a condition or data item and invocations of activities are examples of actions. An action can also be a sequence of actions that occur simultaneously regardless of the sequence of their appearance. Logical conditional actions may be expressed based on conditions or on the occurrence of events. When an action is a sequence of actions, the actions that make it up are separated by semicolons.