The assembly coordinate system describes component position in an assembly along three axes: the X axis (the horizontal reference), the Y axis (the vertical reference), and the Z axis (the depth reference).
In part and assembly files, the origin of the coordinates is represented by the point of intersection (the center point) of three work planes. In the browser, the work planes and center point are listed under the Origin icon. The work planes and the center point are hidden, but you can click to make them visible. You can constrain components to the work planes and center point.
You can position a component relative to the origin of the assembly coordinates. Some companies define the coordinate origin as an absolute point in space from which all other components are positioned. You can reposition components as needed by specifying an offset from the coordinate origin. To specify the offset, right-click the component, select Properties, and then select the Occurrence Property tab.