Patent ID: 7549592

Claim:
A method of embedding information on a substrate, comprising: converting the information to machine readable code format; and writing the machine readable code format comprised of a set of distinguishable symbols including a first symbol and a second symbol, the first symbol and the second symbol respectively encoding a first set of digital values comprised of a first digital value and a second digital value selected from the group consisting of zeroes and ones, on the substrate with at least two fluorescent marking materials, wherein the distinguishable symbols are selected from a group consisting of glyphs and dots, wherein if the first digital value is a zero, the second digital value is a zero or a one, and if the first digital value is a one, the second digital value is a zero or a one, wherein the at least two fluorescent marking materials comprise a first fluorescent marking material containing a first fluorescent material so that upon exposure to radiation effecting fluorescence of the first fluorescent material, the first fluorescent marking material exhibits a first visible color, and a second fluorescent marking material containing a second fluorescent material so that upon exposure to radiation effecting fluorescence of the second fluorescent material, the second fluorescent marking material exhibits a second visible color different from the first visible color, wherein the first visible color and the second visible color respectively encode a second set of digital values selected from the group consisting of zeroes and ones, wherein if the first visible color encodes a zero, the second visible color encodes a one, and if the first visible color encodes a one, the second visible color encodes a zero, and wherein the first symbol is formed by one of either the first fluorescent material or the second fluorescent material and the second symbol is formed by the other of the first fluorescent material or the second fluorescent material.