Figure (coord-axes): The Screen Coordinate System
The MGED editor uses the standard right-handed screen coordinate system, as shown in Figure (coord-axes) . The Z axis is perpendicular to the screen and the positive Z direction is out of the screen. The directions of positive (+) and negative (-) axis rotations are also indicated. For these rotations, the ``Right Hand Rule'' applies: Point the thumb of the right hand along the direction of +X axis and the other fingers will describe the sense of positive rotation.