In an arbitration proceeding an employer appeals from so much of an order as confirms awards with reference to two grievances with costs and refers for hearing and report computation of back pay due an employee in accordance with one of the awards. Order, insofar as appealed from, modified on the law by adding after the word “ confirmed ”, at the end of the first ordering paragraph, the following : “ except as to the third paragraph of the award in grievance 2182 and subdivision (a) of the 4th paragraph of the award in grievance 2202, which portions of the awards are vacated.” As so modified, order unanimously affirmed, without costs. It was beyond the jurisdiction of the arbitrator in construing the contract to provide as he did, that in the event of subsequent arbitration of discharge of the reinstated employee the issue “shall not be the existence of just cause”. The plain pertinent provision in the agreement is precisely to the contrary. There is nothing in the agreement to warrant the provision in the award that employees may not be transferred without their consent. The office of the arbitrator is to construe the agreement. Prior custom or lack of opposition of an employer does not empower the arbitrator to add to the terms of the agreement. Present — Wenzel, Acting P. J., MacCrate, Beldock, Murphy and Ughetta, JJ.