anchor.diff:      %% Default errors field but a non-answer-message and only 3xxx
       %% errors detected means diameter sets neither Result-Code nor
       %% Failed-AVP.
  -    #diameter_packet{msg = answer(Req, Caps)};
  -
  -request(send_double_error, Req, Caps) ->
  -    answer(Req, Caps).
  +    {reply, #diameter_packet{msg = answer(Req, Caps)}};
  +
  +request(T, Req, Caps)
  +  when T == send_double_error;
  +       T == send_missing_avp ->
  +    {reply, answer(Req, Caps)};
  +
  +request(send_ignore_missing_avp, Req, Caps) ->
  +    {reply, #diameter_packet{msg = answer(Req, Caps),
  +                             errors = false}}.  %% ignore errors
   
   answer(Req, Caps) ->
       #diameter_base_STR{'Session-Id' = SId}
  
positive.code:     #diameter_base_STA{'Session-Id' = SId,
                         'Origin-Host' = OH,
                         'Origin-Realm' = OR,
                         'Result-Code' = ?SUCCESS}.
  
negative.code: 
  -include("diameter.hrl").
  -include("diameter_gen_base_rfc6733.hrl").
  %% Use the fact that STR/STA is identical in RFC's 3588 and 6733.
  
  %% ===========================================================================
  
  -define(util, diameter_util).
  -define(testcase(), proplists:get_value(testcase, get(?MODULE))).
  -define(group(Config), begin
                             put(?MODULE, Config),
                             ?util:name(proplists:get_value(group, Config))
                         end).
  
  -define(L, atom_to_list).
  -define(A, list_to_atom).
  
  -define(CLIENT, "CLIENT").
  -define(SERVER, "SERVER").
  -define(REALM, "erlang.org").
  -define(HOST(Host, Realm), Host ++ [$.|Realm]).
  
  -define(ERRORS, [answer, answer_3xxx, callback]).
  -define(RFCS, [rfc3588, rfc6733]).
  -define(DICT(RFC), ?A("diameter_gen_base_" ++ ?L(RFC))).
  -define(DICT, ?DICT(rfc6733)).
  
  -define(COMMON, ?DIAMETER_APP_ID_COMMON).
  
  %% Config for diameter:start_service/2.
  -define(SERVICE(Name, Errors, RFC),
          [{'Origin-Host', Name ++ "." ++ ?REALM},
           {'Origin-Realm', ?REALM},
           {'Host-IP-Address', [{127,0,0,1}]},
           {'Vendor-Id', 12345},
           {'Product-Name', "OTP/diameter"},
           {'Auth-Application-Id', [?COMMON]},
           {application, [{dictionary, ?DICT(RFC)},
                          {module, ?MODULE},
                          {answer_errors, callback},
                          {request_errors, Errors}]}]).
  
  -define(LOGOUT, ?'DIAMETER_BASE_TERMINATION-CAUSE_LOGOUT').
  
  %% ===========================================================================
  
  