53 Pa. Stat. § 30659
It shall be the duty of the city planning commission of said cities to recommend the boundaries of districts and appropriate regulations and restrictions to be imposed therein. Such commission shall make a tentative report and hold public meetings thereon before submitting its final report. At such time as the council may require after such final report, council shall afford persons interested an opportunity to be heard at a time and place to be specified in a notice of hearing to be published for ten consecutive days in two (2) daily newspapers of general circulation in said cities, and the said cities shall not determine the boundaries of any district nor impose any regulations or restrictions until after the final report of the city planning commission and after said hearing before council.
The said cities may, from time to time, after public notice and hearing, amend, supplement, or change said regulations, restrictions, or districts: Provided, That if a protest against a proposed amendment, supplement, or change be presented, duly signed by the owners of twenty (20) per centum or more of the frontage proposed to be altered, or by the owners of twenty (20) per centum of the frontage immediately in the rear thereof, or by the owners of twenty (20) per centum of the frontage directly opposite the frontage proposed to be altered, a three-fourths vote of the members of council shall be required: Provided further, That before any such amendment, supplement, or change shall be voted on by council, the said city planning commission shall have been given by the clerk of council twenty (20) days notice thereof and of the date of hearing: And provided further, That all ordinances passed under the terms of this act shall be enforced by such officer of the city as may be designated by ordinance; and that, upon the application of any aggrieved person, the action or actions of such officer may be reviewed, and affirmed, modified, or reversed, by a board of appeal of three (3) members, one of whom shall be a member of the city planning commission; the said board of appeal and the procedure and the method of such application for review to be provided for by ordinance.
53 P.S. § 30659