Abstract: A method and a system for detecting consignments or items which cannot be conveyed by a conveying system cost-effectively detect non-conveyable items for a materials handling system. A conveyor section and a light grid or curtain or comparable measuring assembly are configured and disposed in such a way that a consignment or item can be conveyed on the conveyor section through the light grid or curtain, so that a data structure characterizing the consignment or item can be generated by the light grid or curtain and fed into the detection system. The detection system is adapted to judge whether the consignment or item is conveyable or not based on the data structure.

Abstract: A value document, in particular a postage stamp, which contains an optically recognizable security element in the form of a two-dimensional structure. Accordingly, the security element has a resolution of at least 300 dpi which makes it difficult to electronically reproduce the security element and therefore protect against the production of counterfeit postage stamps.

Abstract: A forgery-proof value document, in particular a postage stamp, is examined for its authenticity. The value document contains a two-dimensional area with a security element in the form of a two-dimensional structure. The two-dimensional area is provided with, for example printed with, at least one first and at least one other substance. When illuminated with light that is visible to the human eye, the two substances have the same hue and different hues when illuminated with infrared light. The security element is placed on the value document by use the first substance, the remaining part of the area by use of the at least one other substance. When illuminated with visible light the entire two-dimensional area appears in the same hue. When illuminated with infrared light the security element is optically distinguished from the remaining area.