Source : Free On-Line Dictionary of Computing

Universal Character Set
     
         (UCS, ISO/IEC 10646) A 1993 {ISO} and
        {IEC} standard {character set}, also known as "Universal
        Multiple-Octet Coded Character Set".
     
        UCS comes in a 16-bit variant called UCS-2 and a 32-bit
        variant called UCS-4, which is composed of 16-bit UCS-2
        "planes".  So far only one 16-bit plane has been defined,
        which is known as the {Basic Multilingual Plane}.
     
        The implementation of UCS is still in its infancy, though some
        moves, such as the {Java} language defining a character to be
        16 bits, are suggestive.
     
        [Relationship with {Unicode}?]
     
        (1997-07-04)