ActionScript for Flash MX: The Definitive Guide, 2nd Edition By Colin Moock
Chapter 18. ActionScript Language Reference
MovieClip.onRollOver( ) Event Handler
Flash 6
Button event; occurs when the mouse pointer moves over the clip
mc.onRollOver() on (rollOver) { statements }
Description
The onRollOver( ) event handler is identical to the Button.onRollOver( ) event, except that it can also be applied to movie clip instances (though not main movies such as _root, _level0, etc.).