This invention relates to the structure of safety elements for documents and devices for the testing of test documents including said safety elements as well as procedures of application according to patent application DE 197 18 916.4. It is the object of this invention to complete the structure of safety elements by additional safety elements and to contemplate devices for the testing of said safety elements as well as a new application procedure of safety elements and devices which will make it very difficult, if not even impossible, for the counterfeiter to draw any conclusions from the functioning of the test procdures and devices to the safety elements to be tested and, thus, to produce counterfeits that are so similar to the originals that they are not detected by the test devices. The structure of the safety elements for documents to be tested provides a new design not primarily based on a visual examination but on test procedures. This design--hereinafter called functional design--is the combination of electrically conductive and isolating structures having the same or a different size, at the same or different levels to each other, with the same or different conductivities, and it is made of metallized structures and/or conductive inks or printing inks.