Upon becoming either a Class A, a Class B or a Class C member of the Employees’ Retirement System, or upon becoming a member of the Fire and Police Employees’ Retirement System, established under <cite data-path="|22">this </cite><cite data-path="|22">Article 22</cite>, such member shall thereupon be deemed to have entered into a contract with the Mayor and City Council of Baltimore, the terms of which shall be the provisions of <cite data-path="|22">this </cite><cite data-path="|22">Article 22</cite>, as they exist at the effective date of this ordinance, or at the time of becoming a member, whichever is later, and the benefits provided thereunder shall not thereafter be in any way diminished or impaired. City Code, 1966, art. 22, §42 1976/83, art. 22, §42 Ord. 64-426 Ord. 79-1055