If two or more elements or fibers are excited simultaneously, the wave form recorded by a single lead will be the resultant of the electrical activities contributed by each of the discrete elements. If fiber 1 and fiber 2 were excited individually, the generated wave form from each, as recorded by a unipolar electrode positioned between the fibers as shown in the figure, would reflect each individual vector and would be as shown for waveform 1 and waveform 2. When the fibers are excited simultaneously, the wave form generated would reflect the resultant or sum of the two individual vectors as determined by the parallelogram.