Unless otherwise provide by law or in this Zoning Ordinance, no building, structure or land within each district shall be used or occupied except for the express purposes specified for each district in the applicable section of this Zoning Ordinance. Uses, structures and lots existing at the time of passage of this Section, and not in full compliance with the provisions of this Zoning Ordinance, shall comply with the applicable provisions of Sections 1306 Nonconformities.