Fig. 5.

The slide cart coordinate system is found by identifying three locator points on the cart and one point on the fork (shown as solid circles and connected by the dotted lines). A vector connecting the anterior-medial and anterior-lateral points on the distal side of the slide cart form the medial-lateral or x-axis. The cross product of the x-axis with the vector connecting the anterior-medial and posterior-medial points forms the superior/inferior axis or z-axis. The cross product of the z-axis with the x-axis forms the y-axis.