Source : Free On-Line Dictionary of Computing

EIA-530
     
         (Formerly "RS-530") An {EIA}
        {serial line} {standard} which specifies {differential line}
        and {singe ended} communications.  Combining {EIA-422} and
        {EIA-423}, and defining a 25-pin connector for mechanical
        connections, this standard serves as a complement to {EIA-232}
        for high(er) speed data transmissions.
     
        (2002-10-05)