_______days after being requested by either party to do so，give written notice of his decision to the employer and the contractor．subject to arbitration，as hereinafter provided，such decision in respect of every matter so referred shall be final and binding upon the employer and the contractor and shall forthwith be given effect to by the employer and by the contractor，who shall proceed with the execution of the works with all due diligence whether he or the employer requires arbitration, as hereinafter provided，or not．if the engineer has given written notice of his decision to the employer and the contractor and no claim to arbitration has been communicated to him by either the employer or the contractor within a period of _______days from receipt of such notice，the said decision shall remain final and binding upon the employer and the contractor． if the engineer shall fail to give notice of his decision，as aforesaid，within a period of _______ days
after being requested as aforesaid，or if either the employer or the contractor be dissatisfied withany such decision，then and in any such case either the employer or the contractor may within _______ days after receiving notice of such decision，or within _______days after the expiration of the first-named period of _______days，as the case may be，require that the matter or matters in dispute be referred to arbitration as hereinafter provided．all disputes or differences in respect of which the decision，if any，of the engineer has not become final and binding as aforesaid shall be finally settled under the rules of conciliation and arbitration of the international chamber of commerce by one or more arbitrators appointed under such rules．the said arbitrator/s shall have full power to open up，revise and review any decision，opinion， direction, certificate or valuation of the engineer．neither party shall be limited in the proceedings before such arbitrator/s to the evidence or arguments put before the engineer for the purpose of obtaining his said decision．no decision given by the engineer in accordance with the foregoing provisions shall disqualify him from being called as a witness and giving evidence before the arbitrator/s on any matter whatsoever relevant to the dispute or difference referred to the arbitrator/s as aforesaid．the reference to arbitration may proceed notwithstanding that the works shall not then be or be alleged to be complete，provided always that the obligations of the employer，the engineer and the contractor shall not be altered by reason of the arbitration being