53 Pa. Stat. § 23402
Hereafter, for the purpose of fixing their salary or compensation, the patrolmen, police operators, firemen, fire alarm operators, and other officers of the police and fire departments, employed by cities of the second class, shall be divided in classes and officers as follows:
Patrolmen, hosemen, and laddermen shall be divided into seven classes as follows:
The first class shall include all those serving in their first year.
The second class shall include all those serving in their second year.
The third class shall include all those serving in their third year.
The fourth class shall include all those serving in their fourth year.
The fifth class shall include all those serving in their fifth year.
The sixth class shall include all those serving in their sixth year.
The seventh class shall include all those serving in their seventh year or longer.
The officers of the police department shall be divided and classified as follows:
Superintendent, assistant superintendent, inspectors, sergeants, lieutenants, detectives, captains, and police operators.
The officers of the fire department shall be divided and classified as follows:
Chief deputy, chief battalion chiefs, training school instructors, captains, pumpmen, drivers, chiefs' aides, chief fire alarm operator, and fire alarm operators.
53 P.S. § 23402