1. An encoded physical medium suitable for use in interfacing a computer user and a computer system such that the user can control a plurality of computer implemented processes, the encoded physical medium comprising: an encoded information area wherein machine readable linking information has been encoded, the encoded linking information indicating a computer implemented process, the computer system operable to open up the computer implemented process when the encoded information area is selected by the computer user; an encoded instruction area wherein a machine readable operating instruction has been encoded, the encoded operating instruction including an instruction that can be executed by the computer implemented process; wherein the encoded information has been encoded according to a spectral encoding scheme.