Concessional duty eligibility denied for BOPP and Hazy films as plain film; customs to adjust assessments accordingly. Concessional duty under Notification No. 25/99-Cus. for plain plastic films used in electronic capacitor manufacture does not extend to BOPP and Hazy PP films because plain is defined as 'not further worked'; BOPP (oriented) and Hazy (surface treated) films are further worked, differ in physical properties and market identity, and therefore do not qualify. Customs Houses must finalise provisional assessments, and where final assessments previously granted the concession, issue demands for past periods and report action taken.