anchor.diff:      WedgeStatus = fun({_,#p_srvr{address=Addr, port=TcpPort}}) ->
                             machi_flu1_client:wedge_status(Addr, TcpPort)
                     end,
  -    Append = fun({_,#p_srvr{address=Addr, port=TcpPort}}) ->
  +    Append = fun({_,#p_srvr{address=Addr, port=TcpPort}}, EpochID) ->
                        machi_flu1_client:append_chunk(Addr, TcpPort,
  -                                                    ?DUMMY_PV1_EPOCH,
  +                                                    EpochID,
                                                       <<"prefix">>, <<"data">>)
                     end,
       try
           [Start(P) || P <- Ps],
           [{ok, {true, _}} = WedgeStatus(P) || P <- Ps], % all are wedged
  -        [{error,wedged} = Append(P) || P <- Ps], % all are wedged
  +        [{error,wedged} = Append(P, ?DUMMY_PV1_EPOCH) || P <- Ps], % all are wedged
   
           [machi_chain_manager1:set_chain_members(ChMgr, Dict) ||
               ChMgr <- ChMgrs ],
  -        [{ok, {false, _}} = WedgeStatus(P) || P <- Ps], % *not* wedged
  -        [{ok,_} = Append(P) || P <- Ps],                % *not* wedged
  +        {ok, {false, EpochID1}} = WedgeStatus(hd(Ps)),
  +        [{ok, {false, EpochID1}} = WedgeStatus(P) || P <- Ps], % *not* wedged
  +        [{ok,_} = Append(P, EpochID1) || P <- Ps],             % *not* wedged
   
           {_,_,_} = machi_chain_manager1:test_react_to_env(hd(ChMgrs)),
           [begin
  
positive.code:         Proj_mCSum = Proj_m#projection_v1.epoch_csum,
          [{ok, {false, {Epoch_m, Proj_mCSum}}} = WedgeStatus(P) || % *not* wedged
               P <- Ps], 
          [{ok,_} = Append(P) || P <- Ps],                % *not* wedged
  
          %% Stop all but 'a'.
          [ok = machi_flu_psup:stop_flu_package(Name) || {Name,_} <- tl(Ps)],
  
negative.code:         true = (machi_projection:update_dbg2(Proj_m, []) ==
                      machi_projection:update_dbg2(Proj_m, [])),
          %% Confirm that 'a' is wedged
          {error, wedged} = Append(hd(Ps), EpochID2),
          {_, #p_srvr{address=Addr_a, port=TcpPort_a}} = hd(Ps),
          {error, wedged} = machi_flu1_client:read_chunk(
                              Addr_a, TcpPort_a, ?DUMMY_PV1_EPOCH,
  