Description of _root:
specifies or returns a reference to the root movie Timeline. If a movie has multiple levels, the root movie Timeline is on the level containing the currently executing script. For example, if a script in level 1 evaluates _root, _level1 is returned.
Specifying _root is the same as using the slash notation (/) to specify an absolute path within the current level.
The following example stops the Timeline of the level containing the currently executing script:
The following example sends the Timeline in the current level to frame 3:
I dont know do i understand you right but, You can only use _parent to spefic the movieclip...