Being a clause bearing derogation from the general actionability of subjective right positions before ordinary jurisdiction, it is necessary that the arbitration clause be drafted in a precise and unambiguous manner. The arbitration clause is null for genericity and indeterminateness when it entirely lacks any reference to the form and modality of nomination of arbitrators, to specification of the competent arbitral institution and to the place of arbitration, it not being possible to consider clearly determined in the explication of the parties' will to confer an express and specific transactional mandate in favour of arbitrators.