Import and export manifest requirements mandate carrier reporting and Customs permission before unloading or loading cargo. Carriers must furnish an Import General Manifest or import report prior to or on arrival at notified Customs stations; unloading of goods not declared in the IGM is prohibited and unloading occurs under Preventive Customs supervision. For exports, carriers must file an Export General Manifest or Export Report before departure, and loading may not commence without intimation to Customs and permission; Preventive Officers verify completion of customs formalities and export authorization.