A system for N-space navigation of digital data sets comprising an electronic tag having a digitally readable identifier, an electronic tag reader configured to read the identifier of the electronic tag, and a computing system connected to the electronic tag reader to provide digital navigation services...http://www.google.es/patents/US6422474?utm_source=gb-gplus-sharePatente US6422474 - N-space indexing of digital data representations using physical tags
N-space indexing of digital data representations using physical tags
