The Design Zone shall be in the nature of a superimposed zone. Land classified in the Design Zone shall also be classified in one or more other zones. Property so classified shall be delineated on the zoning map by a combination of the zone symbols (for example: ML-D). The regulations set forth in these sections on the Design Zone shall be in addition to the regulations set forth in the underlying zone. In the event the Design Zone is superimposed upon another superimposed zone, the provisions of the Design Zone shall control.
('64 Code, § 49.01)