Relates to engineers' precision straightedges in imperial units. It covers four standard types, and provides for three grades of accuracy. The standard specifies requirements for dimensional accuracy, materials, general quality, finish, marking and packaging together with those design features necessary to ensure convenience in use, rigidity, stability and durability of straightedges. It provides for two varieties of cast-iron staightedges differing in the accuracy of their side faces and designated Type N (normal) and Type S (special).