Flash Timeline
Multiple timelines and levels
Flash Player has a stacking order of levels. Every Flash document has a main Timeline located at level 0 in Flash Player. You can use the loadMovie action to load other Flash documents (SWF files) into Flash Player at different levels.
If you load documents into levels above level 0, the documents stack on top of one another like drawings on transparent paper; when there is no content on the Stage, you can see through to the content on lower levels.
If you load a document into level 0, it replaces the main Timeline. Each document loaded into a level of Flash Player has its own Timeline.
Timelines can send messages to each other with ActionScript. For example, an action on the last frame of one movie clip can tell another movie clip to play. To use ActionScript to control a Timeline, you must use a target path to specify the location of the Timeline.
