Therefore, in a P-D Planned Development District, only existing uses and uses accessory to existing uses are permitted. No additional development of other use may be permitted except as may be allowable after procedures for rezoning of the area to a specific Planned Development District as described by this chapter are fully accomplished and the Zoning Map has been duly amended to designate such area as P-R Planned Residential, P-C Planned Commercial or P-M Planned Manufacturing, or a combination of such planned districts, after preliminary evaluation and review procedures as herein provided.