(1) A sale or purchase of goods shall be deemed to take place in the course of the export of the goods out of the territory of India only if the sale or purchase either occasions such export or is effected by a transfer of documents of title to the goods after the goods have crossed the customs frontiers of India.
     (2) A sale or purchase of goods shall be deemed to take place in the course of the import of the goods into the territory of India only if the sale or purchase either occasions such import or is effected by a transfer of documents of title to the goods before the goods have crossed the customs frontiers of India.
     ¹[(3) Notwithstanding anything contained in sub-section (1), the last sale or purchase of any goods preceding the sale or purchase occasioning the export of those goods out of the territory of India shall also be deemed to be in the course of such export, if such last sale or purchase took place after, and was for the purpose of complying with, the agreement or order for or in relation to such export.]
     ²[(4) The provisions of sub-section (3) shall not apply to any sale or purchase of goods unless the dealer selling the goods furnishes to the prescribed authority in the prescribed manner a declaration duly filled and signed by the exporter to whom the goods are sold in a prescribed form obtained from the prescribed authority.
     (5) Notwithstanding anything contained in sub-section (1), if any designated Indian carrier purchases Aviation Turbine Fuel for the purposes of its international flight, such purchase shall be deemed to take place in the course of the export of goods out of the territory of India.
     Explanation.--For the purposes of this sub-section, "designated Indian carrier" means any carrier which the Central Government may, by notification in the Official Gazette, specify in this behalf.]