Let's start with some well known facts: This example arrow prop is placed on the ground, and points to the sky. The ring at the bottom end of the arrow is at the center of the Poser scene. The coordinates of the center are x=0, y=0, z=0. The length of the prop is about 1 unit, and the upper end of the arrow is at coordinates x=0, y=1, z=0. Before you can rotate the arrow, you define the center of rotation (the "origin", or "Center Point"). The origin can be placed somewhere inside of the arrow body, or at some distance away from the arrow. The center of rotation is the pivot, a (virtual) point, which always stays in place, when the model rotates.