For use with a physical document bearing content visible when illuminated by light in the human visible spectrum, a tag printer, a verifier and a document processing system employing one or both of the printer and the verifier. In one embodiment, the tag printer includes: (1) a processor operable to generate metadata regarding the physical document and (2) a printer associated with the processor and operable to print a tag containing the metadata on a location of the physical document irrespective of locations of the content using an ink substantially invisible in the spectrum.