The characterisation of arbitration as arbitration or contractual arbitration (arbitrato irrituale) constitutes an activity of interpretation of the arbitration agreement reserved to the court, which must ascertain the common intention of the parties as discernible from the tenor of the arbitration clause and from the overall conduct of the contracting parties, without being bound by the formal characterisation adopted by the parties themselves or by the petitum of the action brought; it follows that the court hearing opposition to a payment order founded on an arbitral award may redetermine the nature of the arbitration as arbitration or contractual arbitration (arbitrato irrituale), with the consequential implications as to the efficacy of the award.