(5)For the purposes of this section,-(a)"operation relating to prospecting" means any operation undertaken for the purposes of exploring, locating or proving deposits of any mineral, and includes any such operation which proves to be infructuous or abortive;(b)"year of commercial production" means the previous year in which as a result of any operation relating to prospecting, commercial production of any mineral or any one or more of the minerals in a group of associated minerals specified in Part A or Part B, respectively, of the Seventh Schedule, commences;(c)"relevant previous years" means the ten previous years beginning with the year of commercial production.
