Source : Free On-Line Dictionary of Computing

Technical/Office Protocol
     
        (TOP) An {applications layer} {network} {application} and
        {protocol stack} for {office automation} developed by {Boeing}
        following the {OSI model}.  This {protocol} is very similar to
        {MAP} except at the lowest levels, where it uses {Ethernet}
        ({IEEE} {802.3}) rather than {Token Bus} ({IEEE} {802.4}).