anchor.diff:               Opts,
                Caller,
                SvcName) ->
  -    #diameter_app{module = ModX}
  -        = App,
  -
       Pkt = make_prepare_packet(Mask, Msg),
   
  -    send_req(cb(ModX, prepare_request, [Pkt, SvcName, {TPid, Caps}]),
  +    send_req(cb(App, prepare_request, [Pkt, SvcName, {TPid, Caps}]),
                Pkt,
                Transport,
                Opts,
  
positive.code: 
  %% send_req/6
  
  send_req(Pkt0, {TPid, Caps, App}, Opts, Caller, SvcName, Fs) ->
      #diameter_app{alias = Alias,
                    dictionary = Dict,
                    module = ModX,
                    options = [{answer_errors, AE} | _]}
          = App,
  
      Pkt = encode(Dict, Pkt0, Fs),
  
      #options{filter = Filter,
               timeout = Timeout}
          = Opts,
  
      Req = #request{packet = Pkt0,
                     from = Caller,
                     handler = self(),
                     transport = TPid,
                     caps = Caps,
                     app = Alias,
                     filter = Filter,
                     dictionary = Dict,
                     module = ModX},
  
      try
          TRef = send_request(TPid, Pkt, Req, SvcName, Timeout),
          ack(Caller),
          handle_answer(SvcName, AE, recv_answer(Timeout, SvcName, {TRef, Req}))
      after
          erase_requests(Pkt)
      end.
  
  %% Tell caller a send has been attempted.
  ack({Pid, Ref}) ->
      Pid ! Ref.
  
  %% recv_answer/3
  
  recv_answer(Timeout, SvcName, {TRef, #request{from = {_, Ref}} = Req}) ->
      %% Matching on TRef below ensures we ignore messages that pertain
      %% to a previous transport prior to failover. The answer message
      %% includes the #request{} since it's not necessarily Req; that
  
negative.code:     end;
  
  %% ... answer to known request ...
  recv(false, #request{ref = Ref, handler = Pid} = Req, _, Pkt, Dict0, _) ->
      Pid ! {answer, Ref, Req, Dict0, Pkt};
  %% Note that failover could have happened prior to this message being
  %% received and triggering failback. That is, both a failover message
  