anchor.diff:  read(_Tid, _Ts, Tab, _Key, _LockKind) ->
       abort({bad_type, Tab}).
   
  +-spec first(Tab::table()) -> Key::term().
   first(Tab) ->
       case get(mnesia_activity_state) of
   	{?DEFAULT_ACCESS, Tid, Ts} ->
  
positive.code: first(_Tid, _Ts,Tab) ->
      abort({bad_type, Tab}).
  
  last(Tab) ->
      case get(mnesia_activity_state) of
  	{?DEFAULT_ACCESS, Tid, Ts} ->
  
negative.code: 	    lists:sort(Ts)
      end.
  
  -spec get_index_plugins() -> [IndexPlugins::term()].
  get_index_plugins() ->
      case ?catch_val({schema, user_property, mnesia_index_plugins}) of
  	{'EXIT', _} ->
  