Marketable waste treated as excisable, making bagasse and metal dross liable to excise duty and Cenvat reversal obligations. The statutory amendment expanded excisable goods to include articles, materials or substances arising during manufacture that are capable of being bought and sold; accordingly marketable waste such as bagasse and aluminium/zinc dross are excisable and liable to duty recovery for the post amendment period. Where such products are nil rated or exempt and Cenvat credit has been taken on inputs used for both dutiable and exempt production, the assessee must reverse proportionate credit or pay the alternate prescribed amount. Pre amendment cases remain pending departmental appeal.