GB/T 18780.2-2003
产品几何量技术规范(GPS)几何要素 第2部分;圆柱面和圆锥面的提取中心线、平行平面的提取中心面、提取要素的局部尺寸
Geometrical product specifications(GPS)-geometrical features--Part 2: Extracted median line of a cylinder and a cone,extracted median surface,local size of an extracted feature
GBT18780.2-2003, GB18780.2-2003