US Patent 7872567 Method for transponder access control

A method for transponder access control is disclosed, in which a first identification is stored in the transponder, which is transmitted to a reader unit upon appropriate request by the unit. At least one second identification and an identification selection criterion are stored in the transponder, during a request by the reader unit depending on the identification selection criterion either the first identification or the at least second identification is transmitted and, when the second identification is transmitted, access to the transponder, particularly to the first identification, is released by the transponder when the reader unit transmits a password assigned to the second identification to the transponder.