The manufacture, alteration and repair of special industrial machinery and equipment except metal-working and wood-working machinery, such as food machinery, textile machinery, paper industry machinery, printing-trade machinery and equipment, chemical industry machinery and equipment, oil refining machinery and equipment, cement-making and clay-working machinery, heavy machinery and equipment used by construction and mining industries. The manufacture of material handling machinery, such as lifting and hoisting machines, cranes, conveyors, industrial trucks is classified in group 3829 (Machinery and equipment, except electrical, n.e.c.).