J and Z involve motion. J is I with a twist of the wrist, so that the little finger traces the curve of the printed form of the letter; Z is an index finger moved back and forth, so that the finger traces the zig-zag shape of the letter Z. Both of these "tracings" are made as seen by the signer if right-handed, as shown by the illustrations in this article. When signed with the left hand, the motions are in mirror image, therefore unreversed for the viewer.