Central excise tariff amendment imposes ad valorem duty on polypropylene and copolymers of propylene under notified amendment. The amendment replaces S. No. 4 in the Table to Notification No. 132/86-Central Excises by listing tariff headings 3902.10 and 3902.90 for polypropylene and copolymers of propylene and prescribing an ad valorem duty rate for those entries, effected under sub rule (1) of rule 8 of the Central Excise Rules, 1944.