A node indicates that a state change has occurred. Th numerical ID for the current state and the state that is about to become active is supplied. 

 | Data byte | Description                                                        | 
 | :---------: | -----------                                                        | 
 | 0         | User specified.                                                    | 
 | 1         | Zone for which event applies to (0-255). 255 is all zones.         | 
 | 2         | Sub-zone for which event applies to (0-255). 255 is all sub-zones. | 
 | 3         | State changed from.                                                | 
 | 4         | New State.                                                         | 
