The term "code" refers to the identifier used in a flight schedule, generally the two-character IATA airline designator code and flight number. Thus, XX224 (flight number 224 operated by the airline XX), might also be sold by airline YY as YY568 and by ZZ as ZZ9876. Airlines YY and ZZ are in this case called "marketing airlines" (sometimes abbreviated MKT CXR for "marketing carrier").