Source : Free On-Line Dictionary of Computing

Version 7
     
         (V7) The unsupported release of {Unix}
        ancestral to all current commercial versions.  {Brian
        Kernighan} announced the release of V7 in summer 1979, at the
        {Unix User's} Group meeting in Toronto.
     
        Before the release of the {POSIX}/{SVID} {standard}s, V7's
        features were often treated as a {Unix} portability baseline.
        Some old-timers impatient with commercialisation and {kernel
        bloat} still maintain that V7 was the Last True Unix.
     
        See {BSD}, {USG Unix}, {System V}.
     
        [{Jargon File}]
     
        (1996-05-22)