Systems and techniques are disclosed wherein a method of providing a security code for a document comprises applying a first magnetic feature capable of being read by a contactless magnetic reader and having a fixed magnetic signature selected from a set of magnetic signatures, and applying a second magnetic feature capable of being read by a contactless magnetic reader and characterized by its magnetic signature and its spatial location on the document. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
An automatic identification system and method are provided which employ a machine readable multiple layer label. The label has a plurality of machine readable marking layers stacked one upon another. Each of the marking layers encodes an identification symbol detectable using one or more sensing technologies. The various marking layers may comprise the same marking material or each marking layer may comprise a different medium having characteristics detectable by a different sensing technology. These sensing technologies include x-ray, radar, capacitance, thermal, magnetic and ultrasonic. A complete symbol may be encoded within each marking layer or a symbol may be segmented into fragments which are then divided within a single marking layer or encoded across multiple marking layers.
