For the sake of completeness, let us note that a further remarkable property of flawless VDP samples of plates, foils and layers is the so-called reciprocity. This property, characterising VDP samples, even without respect to their electrical symmetry, is generally understood as self-evident (following from the general reciprocity theorem [11,12]); therefore, it does not perhaps receive due attention by various authors and even its essence does not enter general awareness.