Tariff amendment adds microprocessors and silica preforms to customs exemption table, altering duty rates and conditions. Amendment inserts two new tariff table entries in Notification No. 23/98-Customs: one for microprocessors for automatic data processing machines (other than motherboards) with an adjusted duty measure, and one for preform of silica for manufacture of telecommunication grade optical fibres or optical fibre cables with a distinct duty treatment and related conditional entry.