Patent ID: 7762468

Claim:
A reader to analyze a physical object comprising: an input to receive data corresponding to optical scan data, the optical scan data corresponding to at least a portion of a physical document, the physical document including, first indicia provided on a surface of the object with a first ink or dye, the first ink or dye having a first emission decay rate; second indicia provided on the surface of the object with a second ink or dye, the second ink or dye including a second emission decay rate, wherein the first emission decay rate is relatively shorter than the second emission decay rate, the first indicia and second indicia are arranged on the surface of the object so as to collectively convey a first machine readable code when the first ink or dye and the second ink or dye are excited by non-visible light; and electronic processing circuitry to read a second machine-readable code that is carried by the second indicia, the second machine-readable code becomes readable as emissions from the first ink or dye decrease to at least a first predetermined level, but before the emissions from the second ink or dye decrease to a second predetermined level.