A frame in which you establish exactly what should appear on the Stage at a particular time.
layer
One of a stack of media in a Flash file Timeline. Layers are especially useful in animation because only one object can be tweened per layer when you're using motion tweening.
level
A stacking system for dynamically created or loaded elements. Levels only apply to graphics created with script.
See also [layer]
Library
A storage facility for all media elements used in a Flash file.
