Travaux Préparatoires = "[French 'preparatory work'] Materials used in preparing the ultimate form of an agreement or statute, and especially of international treaty; the draft or legislative history of a treaty." Black's Law Dictionary 1638 (9th ed. 2009).
Travaux Préparatoires, often referred to as travaux, are an important source when interpreting treaties because they can help elucidate the drafters' intent. Consulting travaux is an essential research step when treaty interpretation is at issue.