This part of ISO 8512 specifies requirements for rectangular or square cast iron surface plates ranging from 160 mm ¦ 100 mm to 2 500 mm ¦ 1 600 mm, as preferred sizes, in four grades of accuracy 0, 1, 2 and 3.This part of ISO 8512 applies to new cast iron surface plates, cast iron surface plates in use, and those reconditioned according to their grade.