Source : Free On-Line Dictionary of Computing

V.28
     
         An {ITU-T} physical interface
        standard for {serial} data communications equipment, formally
        titled "Electrical Characteristics for Unbalanced
        Double-Current Interchange Circuits".  The combination of V.28
        and {V.24) is equivalent to the {EIA}'s {RS-232} and uses the
        same 25-pin connectors.
     
        (2001-04-06)