Patent ID: RE39226

Claim:
A machine readable assaying arrangement, comprising: (a) an assay card including a substrate having a surface; and (b) at least one assaying indicia provided upon the surface of the assay card and having an initial encoded value representing a machine readable source of data, the assaying indicia capable of detecting and optically signaling the presence of a desired state, wherein once the desired state is detected the assaying indicia forms a second machine readable encoded value, different from the initial encoded value; (c) each assaying indicia including at least one analysis element, at least one fixed element and at least one blank region therebetween, which collectively form the initial and second encoded values; each analysis element capable of changing from a first state having a first reflectance level to a second state having a second substantially different reflectance level when the desired state is detected, thereby providing an optical change in reflectance producing a change from the initial encoded value to the second encoded value.