Non availment of Modvat certificates: documentary and self declaration rules govern acceptance for duty drawback claims processing. Guidelines require documentary proof of non availment of Modvat for duty drawback claims: certified AR 4 or factory Superintendent certificates for bonded or rebate exports; biannual Assistant Commissioner certificates for dutiable exports without AR 4; self declarations for unconditionally exempt goods or manufacturers outside excise control with possible annual certification; Trade Notices listing exempt goods to relieve certificate requirements; association certificates for unregistered cottage manufacturers; and limitations for merchant exporters sourcing from the open market.