Machinery and fabricated structures for use in the production of oil, gas, water, and other fluids from subterranean wells and for the drilling of such wells, namely, rig structures, namely, [ derricks, drilling masts being parts of machines, ] drilling rigs, [ drill floors for use with drilling rigs, workover rigs used for the repair or stimulation of production wells, off shore and ] on shore drilling rigs [, operator cabins for use with drilling rigs, hoisting machinery, namely, cranes, m...