When buying and offering through a representative and one choice cancels another out. They could both sell or buy yet not do both. AKA either-or purchase and another cancels the other order.
purchase or offer' instruction by litigant to a real estate agent or agent under which execution of just one option preempts others. The agent or agent can either sell that or purchase it, but cannot do both. Also called an either-or purchase, or one-cancels-the-other purchase.