Definition: International tourism expenditures
They are defined as all payments made to carriers registered abroad by any person resident in the compiling country. This category corresponds to "transportation, passenger services, debits" in the standard reporting form of the IMF. However, for tourism purposes we are only interested in the part generated by visitors.
Eurostat, "Methodological manual on the design and implementation of surveys on inbound tourism", Office for Official Publications of the European Communities, Luxembourg, 2000, Appendix A, Classification and Glossary