应该是这样的:
The key tolerance[0.007in/ft (0.59 mm/m)] is the parallelism of the top surface of the head adapters to the head mating surface along with the perpendicularity[0.0005 in (0.01 mm)] of the top surface to the penetration centerline.
这里:
公差(key tolerance)=0.007in/ft (0.59 mm/m)
垂直度(perpendicularity)=0.0005 in (0.01 mm)