A computer-based method for characterizing relationships between a primary goal and an auxiliary goal in an enterprise planning model includes representing the primary goal by a primary objective function, the primary objective function being dependent upon a set of operational variables. Stacker 2 comprises an X-linkage 20 having a driver arm 41 that is separably pushed by head 16 in the same rotational direction as head 16 swings to expand X-linkage 20, to thereby move pusher plate 18 from the initial position to the extended position and to stow the document within interim chamber 24 into storage 7. The portion of the print data that has been stored is concurrently read from the storage device, and sent to the print engine, thereby allowing the print job to be printed as the print job is being stored onto the storage device. The second fixing unit includes a second movable plate, a second actuator, and a second stopper that limits outward movement of the second movable plate. The etching step can be accomplished simultaneously with a step of etching back a patterned oxide layers, such as a shallow trench isolation layer.