46 C.F.R. § 535.104
When used in this part:
(f) Common carrier means a person holding itself out to the general public to provide transportation by water of passengers or cargo between the United States and a foreign country for compensation that:
(2) Utilizes, for all or part of that transportation, a vessel operating on the high seas or the Great Lakes between a port in the United States and a port in a foreign country, except that the term does not include a common carrier engaged in ocean transportation by ferry boat, ocean tramp, or chemical parcel tanker, or by a vessel when primarily engaged in the carriage of perishable agricultural commodities:
(o)
(1) Joint service agreement means an agreement between ocean common carriers operating as a joint venture whereby a separate service is established that:
(hh) Sub-trade means the scope of ocean liner cargo carried between each U.S. port range and each foreign country within the scope of the agreement. U.S. port ranges are defined as follows: