This Ordinance, and as herein used the term ordinance shall be deemed to include the official zoning map or maps, shall not be amended except to correct a manifest error in the ordinance, or, because of changed or changing conditions in a particular area or in the City generally, to rezone an area or to extend the boundary of an existing zone in accordance with the adopted Comprehensive Plan for the City of Newport or to change the regulations and restrictions thereof, only as necessary to the promotion of the public health, safety or general welfare. Subject to the limitations of the foregoing Declaration of Public Policy, an amendment to this Ordinance may be initiated by the Board of City Commissioners or the Planning Commission on their own motion, or in the manner and pursuant to the procedure hereinafter set forth, may be initiated by any person, firm or corporation filing and application therefor with the City.