Within the various zoning districts as herein defined and as indicated on the official zoning map and subject to the requirements of chapter 3 of this title, buildings or structures shall not be erected, reconstructed, or structurally altered, nor shall any land, building or structure be used for any purpose: a) as it is allowed in the district in which such building, land or use is located or b) satisfies the requirements of chapter 5, "Nonconforming Uses", or chapter 6, "Conditional Uses", of this title. (Ord. 1576, 5-1-1989, eff. 6-15-1989)