48Furthermore, as the Commission rightly contends, operating aid, that is to say, aid intended to relieve an undertaking of the expenses which it would itself normally have had to bear in its day-to-day management or its usual activities, does not in principle fall within the scope of Article 92(3) aforesaid, and cannot therefore be regarded as authorized by Decision 75/397 or by the letter of 25 May 1978. According to the relevant case-law, the effect of such aid is in principle to distort competition in the sectors in which it is granted, whilst nevertheless being incapable, by its very nature, of achieving any of the objectives of the aforesaid exceptions (see, in that regard, the judgments of the Court of Justice in Case C-86/89Italy v Commission [1990] ECR I-3891 and in Case C-301/87France v Commission [1990] ECR I-307).