Rebate of duty on excisable materials: conditional refund on export subject to declaration, verification and prescribed export procedures. Rebate of duty on excisable materials used in manufacture or processing of export goods is payable on exportation subject to conditions under rule 18. The manufacturer must file a declaration with the Assistant/Deputy Commissioner detailing finished goods, tariff classification, duty paid on materials and the manufacturing formula. The proper officer verifies input-output ratios and may permit manufacture and export if no likelihood of duty evasion. Procurement, removal for processing, export via Form A.R.E. 2, claim lodging with the jurisdictional Assistant/Deputy Commissioner, and definition of 'duty' are prescribed.