Customs notification amendment postpones effective date for duty exemptions and rates, extending prior deferment in public interest. Amendment to Notification No. 21/2002-Customs substitutes the effective date in the proviso to clause (f), deferring the applicability of exemptions and effective rates of basic and additional customs duty across Chapters 1 to 99; the Central Government exercised its powers under sub-section (1) of section 25 of the Customs Act, 1962, citing public interest and published the change by Notification No. 28/2009-Customs as a further amendment to the principal notification.