 Nachtigall (1974) went the next step, gathering a vast collection of structural schemes for attachment, classifying them by function, and comparing each with its technological analogs.Among interlocking joints he recognizes miters, rabbets, dovetails, and mortises; under releasable attachments he describes plugs and sockets, hooks and eyes, snaps, vises, forceps, anchors, suction cups, and others.The diversity defies summarization.