Specifies requirements for three types of levels, viz. Type 1 which is usually made with a flat unrelieved base of hardened steel, Type 2 which usually has a cast iron body, and Type 3 which is a square block level that may be used for checking both flatness and squareness. Sensitivities of spirit level vials, design features, accuracy requirements and marking are specified and an appendix describes preferred test methods.
