| Interface | Description | 
|---|---|
| Event | An event fired by the observation mechanism. | 
| EventIterator | Allows easy iteration through a list of  Events withnextEventas well as askipmethod inherited fromRangeIterator. | 
| EventListener | An event listener. | 
| EventListenerIterator | Allows easy iteration through a list of  EventListeners withnextEventListeneras well as askipmethod inherited fromRangeIterator. | 
| ObservationManager | The ObservationManager object. |