Customs duty amendment substitutes Nil entry for specified tariff item, changing its effective exemption and duty treatment. The Central Government, invoking its power under section 25(1) of the Customs Act, 1962, amends Notification No. 21/2002-Customs by substituting the entry 'Nil' in column (5) against S.No. 60A in the Table, thereby changing the exemption/effective duty treatment for that tariff item by Notification No. 53/2007-Customs.