Eyeon:Manual/Fusion 6/Tracker/Exp/UnSteady Position

The UnSteady Position can be used to de-stabilize a foreground to match the motion of the tracked background. This picture shows the original motion of the tracked pattern.

When you connect a center control to the UnSteady Position of the Tracker, it will be placed at 0.5/0.5 (the center of the screen) by default at frame 1. This can be changed by means of the Reference Mode in the Tracker's Operation Tab. From there on the resulting motion is basically an offset in the same direction as the original motion.

To explain this further one could say that the resulting motion, once the offset to 0.5/0.5 is acquired, follows exactly the original motion.