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

The Steady Position Mode can be used to stabilize footage in both X and/or Y to remove camera shake and other unwanted movement. This picture shows the original motion of the tracked pattern.

When you connect a center control to the Steady 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 of the Steady Position mode will run in the opposite direction of the original motion.

To explain this further one could say that the resulting point is mirrored around the center between the first frame of the original motion and 0.5/0.5.