ROLL is the instantaneous value of the angle between the reference plane and the horizontal, measured in an athwartship vertical plane. 横摇以从左到右通过舰身的垂直面，量度参考面与水平面之间所形成的即时角度。
This fixture should be provided with a reference leveling surface, so that it can be kept level as the balance deflects. 这种装置应该有一个水平基准面，以便在天平变形时能够使之保持水平。
The grinding surface is also the positioning surface of the workpiece in centerless grinding. 摘要无心磨削中，工件的磨削面就是工件的定位基准面。
