53 Pa. Stat. § 12637
The commission shall classify and grade all positions in the classified service. The commission shall ascertain and record the duties of each position in the service, and, wherever it appears that two or more positions in a service have duties which are substantially similar in respect to the authority, responsibility, and character of work required in the performance thereof, they shall be placed in the same grade, which the commission shall designate by a title indicative of such duties. Grades having duties of the same general nature and in the same line of promotion shall be placed in the same class and the lines of promotion definitely specified. For each grade the commission shall determine a standard maximum and minimum salary or rate of pay, and shall report the same to the mayor and the council, together with other information pertaining to a proper rate of pay for personal services of incumbents of positions in the civil service.
53 P.S. § 12637