Nothing in this Act or the rules made thereunder shall be deemed to impose, or authorise the imposition of a tax on any sale or purchase of any goods when such sale or purchase takes place--
         (i) in the course of inter-State trade or commerce; or
         (ii) outside Delhi; or
         (iii) in the course of the import of the goods into, or export of the goods out of, the territory of India.
     Explanation.--Sections 3, 4, and 5 of the Central Sales Tax Act, 1956 (74 of 1956) shall apply for determining whether or not a particular sale or purchase takes place in the manner indicated in clause (i), clause (ii) or clause (iii) of this section.