53 Pa. Stat. § 13106
Amendments to the charter for the government of any city may be proposed by a resolution of the city council adopted with the concurrence of two-thirds of its elected members. Amendments to a charter adopted under the provisions of this act may also be proposed by a petition presented to the city council of the city. Such petition shall be in the form prescribed by the city council and shall be signed by not less than twenty thousand registered electors of the city and shall set forth the text of the proposed amendments and may designate and authorize not less than three nor more than five of the signers thereto to approve any alteration or change in the form or language or any restatement of the text of the proposed amendments which may be made by the city solicitor or head of the department of law of the city, as provided in section seven of this act. Each elector signing such petition shall add to his signature his occupation and residence and the date of signing. Signatures to the said petition may be on separate sheets but each sheet shall have appended to it the affidavit of some person, not necessarily a signer and not necessarily the same person as on other sheets, that to the best of affiant's knowledge and belief, the signers are registered electors of the city, that they signed with full knowledge of the contents of the petition and that their residences are correctly given. Upon the filing of such petition, as hereinafter provided, the presiding officer of the city council shall, without undue delay, submit for the consideration of the city council the question as to whether the amendments proposed thereby shall be submitted to the qualified electors of the city for their approval or disapproval. If the city council, by a resolution adopted with the concurrence of a majority of its elected members, shall so determine, such proposed amendments shall be submitted to the qualified electors of the city for their approval or disapproval; otherwise, the petition shall be deemed denied. Upon the adoption of a resolution either proposing amendments or to submit to the qualified electors of the city amendments proposed by a petition signed by registered electors, the city council shall forthwith provide, by ordinance, for the submission of the proposed amendments to the qualified electors of the city for their approval or disapproval, at a special election, on the day fixed and designated in the ordinance, in accordance with the provisions of section ten of this act.
53 P.S. § 13106