anchor.diff:      #dpor_state{trace = [TraceTop|_] = Trace} = State,
       #trace_state{i = I, enabled = Enabled, blocked = Blocked,
                    nexts = Nexts, lid_trace = LidTrace,
  -                 clock_map = ClockMap, sleep_set = SleepSet,
  -                 sleep_map = SleepMap} = TraceTop,
  +                 clock_map = ClockMap, sleep_set = SleepSet} = TraceTop,
       NewN = I+1,
       ClockVector = lookup_clock(Lid, ClockMap),
       LidsClockVector = dict:store(Lid, NewN, ClockVector),
  
positive.code:           backtrack = ordsets:new()     :: ordsets:ordset(), %% set(lid:lid()),
            done      = ordsets:new()     :: ordsets:ordset(), %% set(lid:lid()),
            sleep_set = ordsets:new()     :: ordsets:ordset(), %% set(lid:lid()),
            sleep_map = dict:new()        :: dict(), %% dict(lid:lid(), set(lid:lid)),
            clock_map = empty_clock_map() :: clock_map(),
            lid_trace = new_lid_trace()   :: queue() %% queue({transition(), clock_vector()})
           }).
  
negative.code:                     link(Pid),
                      Pid ! ?VECTOR_MSG(Lid, VC),
                      receive
                          ?VECTOR_MSG(_PidsLid, ok) -> ok;
                          {'EXIT', Pid, _Reason} ->
                              %% Process may have been asked to exit.
                              ok                                                        
  