In the matter of the challenge of the arbitral award, the subsequent formation of res judicata on the termination of the works contract renders the enquiry into the timeliness and adequacy of the reservations entered by the contractor superfluous, such reservations being deemed, pursuant to art. 1458 cod. civ., to have lapsed together with all other effects of the contract. The obligation to enter reservations, the function of which is to ensure the timely and ongoing identification of all factors liable to increase the total consideration, presupposes the existence of a valid contract of which performance is sought, whereas, where the issue is the invalidity of the contract or the manner of its termination, the claims arising from the breach by the contracting authority are governed by the general principles set out in artt. 1453 and 1458 cod. civ.