The+appeal+to the arbitration+not+is+excluded,+in+line+of+principle,+for+the+issues+relevant+to+nullity+of the+contracts,+permitting+in+matter+rights+available,+being certainly+available+the+right+a+to do+the+nul lity+of+a+contract+or+of+a+resolution.+indeed,+the+limit+of the+unavailability+of the+rights+not+it must be confused+with+the+of the+mandatory+of the+legislation+substantial+applicable+to the+case+controversial,+and+which+gives+place+a+nullity.