Modvat credit acceptance of PSU certificate allows manufacturers to claim input credit for imported colour picture tubes under countervailing duty Where inputs are canalized by a public sector undertaking, a certificate issued by that undertaking endorsing payment of countervailing duty qualifies as sufficient proof for assessees to claim Modvat credit; gate passes or buyer-end bills of entry should not be insisted upon. This procedure in the Modvat Guide is to be applied to colour picture tubes imported by the specified public sector undertaking so that manufacturers supplied by it may claim input credit on the basis of the undertaking's certificate.