Voucher with self-contained verification means

Claim 1

A family of vouchers, each voucher comprising a substrate: correlatable first and second identifying indicia located in separate locations on a surface of the substrate, the first indicia in a first of the locations being visible to the eye in the original condition of the voucher; the second indicia being located at a second of the locations; a release coating layer at the upper surface of the second indicia; and a readily removable outer coating layer overlying the release coating layer; wherein the materials of which the substrate, indicia and layers are made at least in the vicinity of the second location are selected and the surface conditions of the substrate and layers at least in the vicinity of the second location are selected such that the adhesion between the release coating layer and the outer coating layer is relatively low, the adhesion between the release coating layer and the substrate is relatively high, the adhesion between the outer coating layer and the substrate is relatively high, and the outer coating layer tends to disintegrate as a consequence of the step of removing same, such that upon removal of the outer coating layer, the second indicia in the second location are visible to the eye, the second indicia being difficult to alter without detection by reason of the said selections; each voucher in the family of vouchers having individual and unique identifying indicia, and wherein the elements constituting the second indicia are in at least one dimension randomly spaced on the voucher within the area covered by the release coating and outer coating layers so that the exact location of the elements constituting the second indicia cannot be readily determined without removing the outer coating layer.