Unless the context clearly requires otherwise, as used in this chapter, the following terms have the following meanings:

(1) SECRETARY. The Secretary of the Department of Labor or such other public officer, employee, board, commission, or other authority that may by law be assigned the duties and authority of the Secretary of Labor under this chapter.

(2) CHIEF. The Chief of the Division of Safety and Inspection of the Department of Labor or such other public officer, employee, board, commission, or other authority that may in emergencies be acting in the stead of the chief or may by law be assigned the duties and authority of the Chief of the Division of Safety and Inspection of the Department of Labor.

(3) HEAD MINE INSPECTOR. The employee of the Division of Safety and Inspection in charge of mine inspection or such other public officer, employee, board, commission, or other authority that may by law be assigned the duties and authority of the head mine inspector.

(4) MINE INSPECTOR. A public employee assigned by the head mine inspector with the approval of the chief to make mine inspections as required by this chapter and other laws from time to time in such cases made and provided.

(5) SUPERINTENDENT. The person placed in overall charge of the operation of a coal mine or mines.

(6) OPERATOR. The owner, part owner, operator or lessee to whom the superintendent reports and is accountable for the operation. The operator may also be the superintendent.

(7) MINE FOREMAN. A person holding a valid certificate of qualification duly issued by action of the board of mine examiners. Such term also includes the person acting in the stead of a mine foreman appointed as provided under this chapter when a certified mine foreman is unavailable.

(8) SUPERVISOR. Such term may be used to designate mine foremen, assistants, section foremen, trafficmen, maintenance foremen, etc., and is restricted in this chapter to mean those persons employed by the operator or superintendent to manage all or a part of the mine operations.

(9) FIRE BOSS. A person holding a valid certificate of qualification duly issued by action of the board of mine examiners and also includes the person acting in the stead of a fire boss appointed as provided under this chapter when a certified fire boss is unavailable.

(10) APPROVED COMPETENT PERSON. A person who has at least nine months of practical experience, has knowledge of mine roof, timbering, and ventilation, has good judgment and who has demonstrated knowledge of mine gases and use of permissible flame safety lamps, methane and oxygen detectors, such demonstration to be given and made of record in a manner prescribed by the chief of the division.

(11) APPROVED. A device, process, equipment, or method approved by the chief; provided, that if any interested person so requests, the secretary shall review such approval.

(12) PERMISSIBLE. A device, process, or equipment or method heretofore or hereafter classified by such term by the United States Bureau of Mines when such classification is adopted by the chief and includes, unless otherwise expressly stated in this chapter, all requirements, restrictions, exceptions, limitations, and conditions attached to such classification by said bureau.