anchor.diff:  
   %% transition/2
   
  -%% Listening process is transfering ownership of an association.
  -transition({peeloff, Sock, {sctp, LSock, _RA, _RP, _Data} = Msg, Matches},
  -           #transport{mode = {accept, _},
  -                      socket = LSock}
  -           = S) ->
  -    ok = accept_peer(Sock, Matches),
  -    transition(setelement(2, Msg, Sock), S#transport{socket = Sock});
  -
   %% Incoming message.
   transition({sctp, Sock, _RA, _RP, Data}, #transport{socket = Sock} = S) ->
       setopts(Sock),
  
positive.code:                mode = {connect, connect(Sock, RAs, RP, [])},
                 socket = Sock};
  
  %% An accepting transport spawned by diameter.
  i({accept, Pid, LPid, Sock, Ref})
    when is_pid(Pid) ->
      putr(?REF_KEY, Ref),
      proc_lib:init_ack({ok, self()}),
      monitor(process, Pid),
      monitor(process, LPid),
      #transport{parent = Pid,
                 mode = {accept, LPid},
                 socket = Sock};
  
  %% An accepting transport spawned at association establishment.
  i({accept, Ref, LPid, Sock, Id}) ->
      putr(?REF_KEY, Ref),
      proc_lib:init_ack({ok, self()}),
      MRef = monitor(process, LPid),
      %% Wait for a signal that the transport has been started before
      %% processing other messages.
      receive
          {Ref, Pid} ->  %% transport started
              #transport{parent = Pid,
                         mode = {accept, LPid},
                         socket = Sock};
          {'DOWN', MRef, process, _, _} = T ->  %% listener down
              close(Sock, Id),
              x(T)
      after ?ACCEPT_TIMEOUT ->
              close(Sock, Id),
              x(timeout)
      end.
  
  %% close/2
  
negative.code: %% Ditto but we have ownership of the association. It might be that
  %% we'll go down anyway though.
  transition({'DOWN', _, process, _Pid, _}, #transport{mode = accept}) ->
      ok;
  
  %% Timeout after transport process has been started.
  transition(accept_timeout, _) ->
      ok;
  
  %% Request for the local port number.
  