Product classification: Cardenol treated as cashew-industry product and eligible for central excise exemption after purification. Cardenol is obtained by purification/distillation of Cashew Nut Shell Liquid (CNSL); chemical tests show no change in molecular structure and administrative inputs classify cardenol producers as part of the cashew industry. Prevailing authority treats distillation purification as not amounting to manufacture, and consequently Cardenol is a product of the cashew industry and eligible for central excise exemption.