Foreign trade zone

A port designated by the Government of a country for dutyfree entry of any nonprohibited goods. Merchandise may be stored, displayed, used for manufacturing, etc. within the zone and reexported without duties being paid. Duties are imposed on the merchandise (or items manufactured from the merchandise) only when the goods pass from zone into an area of the country subject to the Customs authority.
(Air Cargo from A to Z, Air Transport Association of America)