ISO 18000-6 is a proposed international standard governing the way tags and readers communicate in the UHF spectrum. There are currently two versions, 18000-6A and 18000-6B. It is possible that EPCglobal's Gen 2 standard could become an international standard and be called ISO 18000-6C, but as of December 2004, the Gen 2 standard did not include an 8-bit application family identifier, which would be required for it to be an ISO 18000-6 standard.