Specifies requirements for single start parallel coarse pitch series metric screw threads, mainly intended for threaded fasteners. It covers screw threads from 1.6 mm diameter up to and including 64 mm diameter, in tolerance classes 6e, 6f, 6g and 8g, for external threads; and 6H and 6G for internal threads. Information is given on symbols for screw thread parameters, tolerances, deviations, thread classes, designation and verification. Appendices, giving notes on the production of screw threads and a comparison of symbols used in This Standard and the 1972 edition, are included. It should be particularly noted that in this edition, the thread roots of external threads (root curvature and associated limits and tolerances), are specified in a manner that is fundamentally different from the 1972 edition.