From Second Life Wiki
|LSL Portal||Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials|
The integer constant CHANGED_REGION has the value
The object has changed region by crossing a region boundary (or by teleporting, if attached). This event only occurs in the root prim of a linkset. This event does not occur in child prims of objects when they cross a region boundary.
integer CHANGED_REGION = 0x100;