The D Design and Development Control Overlay District may be combined with any zoning district. It may be initiated by the Planning Commission or the City Council under the procedures established by Article 26, Amendments. Each D overlay district shall be shown on the zoning map by adding a “-D1,” “-D2,” or “-D3” designator, as the case may be, to the base district designation. Each D2 designator shall be followed by a reference to the ordinance adopting the district which includes the required findings and any specific conditions or standards applying to development within the district. A D2 designation shall only be applied when rezoning a property from one base district to another.