An award rendered in contractual arbitration (arbitrato irrituale), being contractual in nature, may form the basis of a monetary claim pursued by way of summary proceedings for an order for payment and constitutes, together with the documents produced, evidence sufficient for the issue of a decreto ingiuntivo (order for payment) under arts. 633 et seq. cod. proc. civ., provided that it shows a debt which is certain, ascertained in amount and due.