This major category includes occupations concerned with the operation of machines that cut, bore, mill, abrade, print, and similarly work such materials as metal, paper, wood, plastics, and stone. A worker's relationship to the machine is of primary importance. In other jobs eye and hand coordination may be the most significant factor. Includes occupations concerned with installation, repair, and maintenance of machines and mechanical equipment.

This subcategory includes occupations concerned with installing, inspecting, testing, repairing, rebuilding, and maintaining in efficient operating condition all types of engines and a wide variety of mechanical equipment designed for general or specific application.

This subcategory includes occupations concerned with reproducing data or designs by mechanical transfer of ink or dye to the surface of materials with the aid of type, plates, rolls, and the like. Includes the preparation of type and plate for machines and mechanical bookbinding.