In a grievance against petitioner's employer, which was referred to an arbitrator pursuant to a collective bargaining agreement, the arbitrator's dismissal of the grievance as not arbitrable on the ground that a four-month deadline for holding a hearing, as required by the agreement, had passed, is reversed where: 1) the arbitrator erred because the contractual provision does not require dismissal of the grievance in the event of noncompliance with the four-month deadline; and 2) the deadline is merely a nonbinding housekeeping rule to encourage timely arbitration, one that is addressed to the arbitrator as well as the parties.