Customs tariff amendment reduces prior ad valorem exemption rate under Customs Act, altering two exemption notifications. The Central Government, under sub-section (1) of section 25 of the Customs Act, 1962, amends Notification Nos. 55/87-Customs and 56/87-Customs by substituting the previously stated ad valorem rate in each notification with a revised lower ad valorem rate, thereby changing the tariff exemption terms in those notifications.