DATA-PROTECTED DIGITAL RECORDING MEDIUM

摘要

In one embodiment, a digital recording medium having digital datum indicia thereon readable by a reader producing a read-wave, the digital recording medium comprising: a photochrome materia] activatable from a first optical state to a second optical state by radiant energy having energy outside of the read-wave of the reader; and a photobleachable material activatable from a first optical state to a second optical state by radiant energy having energy within the read-wave of the reader.