In the global scale, trading activities of some of the goods in country and world markets, for example their imports are limited by certain quotas to ensure that they are not traded below a specific unit price in order to prevent an unfair competition that may harm the local producers of those goods. Thus, before doing an import plan for goods that you plan to import, you must perform a preliminary research.  Many importers, who are not aware that the goods they are planning to import are subject to an inspection certificate or quote, find out the need for such a permit only after their goods arrive to the customs and thus they had to pay high amounts of warehouse fee since their goods have to wait in customs until the permit is received.