A line of punch positions parallel to the Y datum line of a punch card.
2
垂直度-条件是表面,轴,或线,这是90度的基准平面或基准轴。
Perpendicularity - is the condition of a surface, axis, or line, which is 90 deg. From a datum plane or a datum axis.
3
此法可避免频琐的作图和手工计算,迅速、准确地对四种基准平面的平面度进行评定。
By using this method, not only overelaborate drawing and hand-calculating can be avoided, but also the flatness of four kinds of datum-planes can be assessed quickly and precisely.