anchor.diff:  
   %% incr/4
   
  -incr(F, A, SA, AM)
  -  when F == 'AVP';
  -       A == ?ANY;
  +incr(_, A, SA, AM)
  +  when A == ?ANY;
          A == 0;
          SA /= decode ->
       {undefined, AM};
  
positive.code: 
  incr(Name, Code, Vid, M, Mod, Strict, Opts, AM0) ->
      NameT = Mod:avp_name(Code, Vid), %% {AvpName, Type} | 'AVP'
      AvpName = field(NameT),
      Arity = avp_arity(Name, AvpName, Mod, Opts, M),
      {NameT, AvpName, Arity, incr(AvpName, Arity, Strict, AM0)}.
  
  %% Data is a truncated header if command_code = undefined, otherwise
  %% payload bytes. The former is padded to the length of a header if
  
negative.code:     [Failed | Rec] = Acc,
      [[{rc(Avp), Avp} | Failed] | Rec];
  
  %% Relaxed arities.
  acc2(Acc, Avp, _, _, AvpName, Arity, Strict, Mod, _)
    when Strict /= decode ->
  