End fittings may be designed so that they connect to each other in more than two configurations. A first end fitting may be connected to an adjoining end fitting, removed, rotated ninety degrees and reconnected with the adjoining end fitting without jeopardizing stability of the position of each end fitting relative to the other. The first end fitting may be connected to the adjoining end fitting, removed, rotated an additional ninety degrees and reconnected with the adjoining end fitting without jeopardizing stability of the position of each end fitting relative to the other. The first end fitting may be connected to an adjoining end fitting, removed, rotated a yet further ninety degrees and reconnected with the adjoining end fitting without jeopardizing stability of the position of each end fitting relative to the other.