三、形位公差的基准图样上应规定基准,以便表示标注形位公差的形体与基准形体之间的设计关系。基准可以是圆形或棱柱形(六角形、方形等)形体的轴线、公共轴线、中心点或中心平面,也可以是某一形体的平面。圆形形体基准实际上是相互垂直的两个平面。 Third, the shape of the tolerances of the reference pattern should be provided on the benchmark, in order to indicate the form of tolerances and the reference form the body of the relationship between the design. The datum may be a circular or prismatic (hexagonal, square, etc.) body axis, a common axis, a center point or a center plane, or may be a plane of a body. The circular body datum is actually two planes that are perpendicular to each other.