UTP and Screened Telecommunications Outlet/Connector 8-position modular jack per IEC 60603-7 ('568-B.1 states that all 4 pairs must be connected). Pin/pair assignment: T568A (US federal government publication NCS, FTR 1090-1997 recognizes designation T568A only). Optional assignment to accommodate certain systems: T568B. Durability rating 750 mating cycles minimum. Backward compatibility and interoperability is required.