1. Document of value with at least one window area ( 2 , 3 , 4 ) with one polarization element each, which, by a defined angle (p), rotates a plane of polarization of a linearly polarized light beam (L) passing through the associated window area, and the plane of polarization is rotated by a corresponding multiple of such angle when the light beam passes through the window areas of several of these documents of value lying one on top of the other.