6. The system of claim 1 wherein said variable field comprises: a generator identifier field, adjacent said version field, containing a generator identifier string of at least one character, identifying a unique token generator; a verification field, adjacent said generator identifier field, containing a verification character; and an identification field, adjacent said verification field, containing an identification string of at least one character, wherein said identification string is unique for a unique token generator.
7. The system of claim 6 wherein the generator identifier string and the identification string are of variable lengths.