In Midland Borough School District v. Midland Education Association PSEA, 532 Pa. 530, 616 A.2d 633 (1992), while a CBA was still in effect, the school district entered into an agreement with a neighboring school district to transfer all the students from one if its schools to that other district on a tuition basis, thereby eliminating all teaching positions in the grades affected and resulting in building closure. The union filed a grievance, contending that the school district violated the CBA by subcontracting-out bargaining unit work. Ultimately, an arbitrator sustained the union's grievance and, after the contract had expired, directed the school district to, inter alia, rescind the contract with the other district and return the teachers to work. Common pleas vacated that part of the award rescinding the contract and directing the school district to rehire the teachers. Both this court and our Supreme Court affirmed on appeal. In doing so, the Supreme Court emphasized that an arbitrator's authority is defined and limited by the terms of the agreement and the award must represent a legitimate interpretation thereof. The court did not hold that all post-expiration relief exceeds an arbitrator's jurisdiction. In fact, the court noted that, "under certain circumstances particular remedies awarded may in fact continue in effect beyond the expiration of the controlling agreement . . . ." 532 Pa. at 541 n.3, 616 A.2d at 639 n.3. The court concluded, however, that the remedy in those circumstances exceeded the arbitrator's jurisdiction and failed the essence test because it required the school district to open a closed school and re-employ teachers two years after the agreement had expired. Clearly, the remedy exceeded the relevant CBA's temporal parameters, which bound the parties and limited the arbitrator.