scope:

12.1 SCOPE 12.1.1 Purpose. This section establishes the method of representing and specifying threads on Engineering Drawings for both Inch and Metric callouts. Straight unified inch 'UN", "UNR", "UNJ", form and metric "M", "MJ" form screw threads are emphasized in this SECTION in consideration of their wide use and general purpose applications. The same drafting practices apply to straight and taper pipe threads, Acme, Stub Acme, Buttress, Helical coil insert and interference fit threads except for differences noted.