Magnetic recording medium having authenticating poles at its edge

摘要

A magnetic recording medium includes a truth determining code for determining whether the medium is authentic. The truth determining code is indicated by a magnetic polarity at at least an edge of the medium. A method of determining whether the medium is authentic comprises the steps of detecting a magnetic polarity at an edge of the magnetic recording medium, and collating a combination of the magnetic polarity with a proper combination of the magnetic polarity.