71In determining whether an agreement whereby a public authority undertakes to purchase certain services from a specific undertaking for a number of years falls within the scope of Article 92(1) of the Treaty, it must be borne in mind that the aim of Article 92 is to prevent trade between Member States from being affected by advantages given by the public authorities which, in various forms, distort or threaten to distort competition by favouring certain undertakings or the production of certain goods (see Italy v Commission, cited above, paragraph 26, and Case 310/85Deufil v Commission [1987] ECR 901, paragraph 8). It follows that a State measure in favour of an undertaking, which takes the form of an agreement to purchase travel vouchers cannot be excluded in principle from the concept of State aid in the sense contemplated in Article 92 of the Treaty, merely because the parties undertake reciprocal commitments.