The City Council shall by ordinance establish a personnel system for the selection, employment, classification, advancement, demotion, suspension and discharge of those appointive officers and employees who shall be included in the system. The system may consist of the establishment of minimum standards of employment and qualifications for the various classes of employment, or of a comprehensive system, as the City Council shall determine to be for the best interest of the public service. The ordinance shall designate the departments and the appointive officers and employees who shall be included within the system. By subsequent ordinances the City Council may amend the system or the list of departments and appointive officers and employees included within the system. The system shall comply with all other provisions of this Charter.