Post-export conversion of shipping bills clarified with time limits, discretionary extensions, documentary evidence and fee conditions. Applications for post-export conversion must be filed in writing within one year of the clearance order, with discretionary extensions available from the jurisdictional Commissioner and Chief Commissioner where the exporter was prevented from applying; periods of judicial stay are excluded. The Commissioner may authorize conversion based on documentary evidence existing at export, subject to regulation conditions and payment of the prescribed fee, and should, where possible, decide each application within thirty days of filing.