In this chapter, the following terms have the meanings indicated. Terms Defined. “Certificate of competence” means certification that is obtained by a person through any organization accredited by the American National Standards Institute or the National Commission for Certifying Agencies and that states the holder of the certificate demonstrates knowledge of and training in safe crane operating procedures. “Commissioner” means the Commissioner of Labor and Industry. “Crane operator” means an individual who operates a crane. “Digger derrick truck” means a mobile derrick truck with a mast or equivalent member for drilling. “Hydraulic crane” means a crane that has a revolving superstructure, boom, and hoisting machine that is operated, extended, retracted, rotated, raised, and lowered hydraulically. “Inspection of a crane” means a thorough examination of the operation of mechanisms to determine functionality and control of hoisting systems, power transmission equipment, braking, superstructure movement, boom operation, and travel. “Knuckle boom crane” means a hydraulically powered articulating arm fitted to a truck or trailer that is used for loading and unloading the vehicle. It is also known as a loader crane. “Power-operated derrick” means an apparatus consisting of a mast or equivalent member held at the end by guys or braces, with or without a boom, including conventional lattice boom cranes. “Tower crane” means a power-operated hoisting machine in which a boom or structural member is mounted upon a vertical mast or tower structure with the function of hoisting, lowering, and swinging loads at various radii, but does not include a conventional boom, including mobile and track. “Trolley boom” means a crane having a hoist/trolley assembly that runs horizontally along rails.