anchor.diff:       send_protocol_error,
        send_arbitrary,
        send_unknown,
  +     send_unknown_short,
        send_unknown_mandatory,
  +     send_unknown_short_mandatory,
        send_noreply,
        send_unsupported,
        send_unsupported_app,
  
positive.code:                    is_mandatory = true,
                     data = <<17>>}]
          = As.
  
  %% Send an STR that the server ignores.
  send_noreply(Config) ->
  
negative.code:     io:format("~p: ~p~n", [T,P]).
  
  %% prepare/4
  
  prepare(Pkt, Caps, N, #group{client_dict0 = Dict0} = Group)
    when N == send_unknown_short_mandatory;
         N == send_unknown_short ->
      Req = prepare(Pkt, Caps, Group),
  
      #diameter_packet{header = #diameter_header{length = L},
                       bin = Bin}
          = E
          = diameter_codec:encode(Dict0, Pkt#diameter_packet{msg = Req}),
  
      %% Find the unknown AVP data at the end of the message and alter
      %% its length header.
  
      {Padding, [17|_]} = lists:splitwith(fun(C) -> C == 0 end,
                                         lists:reverse(binary_to_list(Bin))),
  
      Offset = L - length(Padding) - 4,
      <<H:Offset/binary, Len:24, T/binary>> = Bin,
      E#diameter_packet{bin = <<H/binary, (Len+9):24, T/binary>>};
  
  prepare(Pkt, Caps, N, #group{client_dict0 = Dict0} = Group)
    when N == send_long_avp_length;
  