anchor.diff:  %% retain the same structure as in diameter_packet.avps, but an 'AVP'
   %% list has always been flat.
   
  -%% acc2/8
  +%% acc2/7
   
   %% No errors, but nowhere to pack.
  -acc2(Acc, Avp, _, 'AVP', 0, _, _, _) ->
  +acc2(Acc, Avp, _, 'AVP', 0, _, _) ->
       [Failed | Rec] = Acc,
       [[{rc(Avp), Avp} | Failed] | Rec];
   
   %% Relaxed arities.
  -acc2(Acc, Avp, _, Field, Arity, Strict, Mod, _)
  +acc2(Acc, Avp, _, Field, Arity, Strict, Mod)
     when Strict /= decode ->
       pack(Arity, Field, Avp, Mod, Acc);
   
   %% No maximum arity.
  -acc2(Acc, Avp, _, Field, {_,'*'} = Arity, _, Mod, _) ->
  +acc2(Acc, Avp, _, Field, {_,'*'} = Arity, _, Mod) ->
       pack(Arity, Field, Avp, Mod, Acc);
   
   %% Or check.
  -acc2(Acc, Avp, I, Field, Arity, _, Mod, _) ->
  +acc2(Acc, Avp, I, Field, Arity, _, Mod) ->
       Mx = max_arity(Arity),
       if Mx =< I ->
               [Failed | Rec] = Acc,
  
positive.code: 
              Dec = dec(Data, Name, NameT, Mod, Fmt, Opts, Avp),
              Acc = decode(T, Name, Mod, Fmt, Strict, Opts0, Idx+1, AM),%% recurse
              acc(Acc, Dec, I, Field, Arity, Strict, Mod, Opts);
          _ ->
              {NameT, _Field, _Arity, {_, AM}}
                  = incr(Name, Code, Vid, M, Mod, Strict, Opts0, AM0),
  
negative.code: set_failed(_, Opts) ->
      Opts.
  
  %% acc/7
  
  acc([AM | Acc], As, I, Field, Arity, Strict, Mod) ->
      [AM | acc1(Acc, As, I, Field, Arity, Strict, Mod)].
  
  %% acc1/7
  
  %% Faulty AVP, not grouped.
  acc1(Acc, {_RC, Avp} = E, _, _, _, _, _) ->
      [Avps, Failed | Rec] = Acc,
      [[Avp | Avps], [E | Failed] | Rec];
  
  %% Faulty component in grouped AVP.
  acc1(Acc, {RC, As, Avp}, _, _, _, _, _) ->
      [Avps, Failed | Rec] = Acc,
      [[As | Avps], [{RC, Avp} | Failed] | Rec];
  
  %% Grouped AVP ...
  acc1([Avps | Acc], [Avp|_] = As, I, Field, Arity, Strict, Mod) ->
      [[As|Avps] | acc2(Acc, Avp, I, Field, Arity, Strict, Mod)];
  
  %% ... or not.
  acc1([Avps | Acc], Avp, I, Field, Arity, Strict, Mod) ->
      [[Avp|Avps] | acc2(Acc, Avp, I, Field, Arity, Strict, Mod)].
  
  %% The component list of a Grouped AVP is discarded when packing into
  %% the record (or equivalent): the values in an 'AVP' field are
  