MODVAT non availment verification: customs must link AR 5 evidence to shipping bills before claiming drawback entitlement. Customs must verify availment of input rebate (MODVAT) by linking the sextuplicate copy of the AR 5 accompanying the consignment to the relevant shipping bill; merchant exporters buying from the open market do not avail input rebate under Rules 12(1)(b)/13(1)(b) unless AR 5 procedure is followed, and manufacturer exporters under AR 4 must indicate availment and enclose AR 5 as evidence before drawback payment.