 The solid vertical lines downward from agt and pat indicate that for any verb integrated into this construction it is required that its subject NP should express the agent participant, and the direct object (OBJ2) should express the patient participant. The dashed vertical line downward from rec signals that the first object (OBJ) may express the recipient but it does not have to—the necessity of there being a recipient is a property of the construction itself, and not every verb demands that it be made explicit who the recipient is. But if there are two objects, the first is obligatorily associated with the recipient role: We sent the builder a carpenter can only express a claim about the sending of a carpenter over to the builder, never the sending of the builder over to where a carpenter is.