Rescission of anti-dumping duty on metronidazole imports from China removes the prior duty under the customs tariff framework. Rescission of anti-dumping duty on metronidazole imported from the People's Republic of China removes the prior notification imposing that duty prospectively, while preserving actions completed before rescission. The central government invokes statutory authority under the Customs Tariff Act and the anti-dumping rules to administratively revoke the earlier notification, affecting future tariff treatment of the specified pharmaceutical import.