第二版取消并取代了第一版（ISO 299:1973），第一版删除了以英寸为单位的尺寸，并增加了第5条。以毫米为单位指定T形槽的尺寸和间距。它还规定了这些槽中使用的螺栓的公制尺寸。

This second edition cancels and replaces the first edition (ISO 299 : 1973), of which the dimensions in inches have been deleted and to which clause 5 has been added. Specifies, in millimetres, the dimensions and spacing of T-slots. It also specifies the metric dimensions of bolts to be used in these slots.