When you drag a grip, the current cursor position is typically projected to the XY plane of the current User Coordinate System (UCS). Some grip-editing operations are not possible in the current coordinate system. For example, if the current UCS is in plan, you cannot change the height of a wall while in an isometric view. For this reason, some grips have their own coordinate system that is temporarily set while the grip is active. Once the grip-editing operation is complete, the UCS is set back to its previous state. To identify whether a grip is setting a temporary coordinate system, set the UCSICON system variable to On on the command line, and display the icon at the origin.