In other words, an assignment clause allows the buyer of a home to sell the place before they take possession of it. In Ontario, assignments are more common in pre-built homes and condos than on re-sale properties, but they are possible on any type of trade.
The initial contract must provide for the possibility of assignment by one of the initial contracting parties. The assignor must agree to assign their rights and duties under the contract to the assignee. The assignee must agree to accept, or "assume," those contractual rights and duties.