The root Movie Clip Hierarchy

An individual Flash movie consists of a root timeline (main timeline) and movie clips which are sub "timelines" attached to the root timeline or nested within other movie clips.

Movie clips can address each other and interact by using a target path.

Example, target path to the variable, "_alpha" in movie clip, "mc1a":

Slash Syntax (deprecated): mc1/mc1a:_alpha

Dot Syntax: _root.mc1.mc1a._alpha

Array Syntax: _root["mc1"].["mc1a"]._alpha