anchor.diff:  
   encode_nsec_types([]) -> <<>>;
   encode_nsec_types([_|_]=UnsortedTypes) ->
  -    [FirstType|_] = Types = unique_list([int_or_badarg(fun type_to_int/1, Type)
  -				     || Type <- UnsortedTypes ]),
  +    [FirstType|_] = Types = lists:usort([int_or_badarg(fun type_to_int/1, Type)
  +					 || Type <- UnsortedTypes ]),
       FirstWindowNum = FirstType div 256,
       FirstLastType = FirstWindowNum * 256,
       encode_nsec_types(<<>>, <<>>, FirstWindowNum, FirstLastType, Types).
  
positive.code:     decode_nxt_bmp(Offset + 1, Rest, Types).
  
  encode_nxt_bmp(UnsortedTypes) when is_list(UnsortedTypes) ->
      Types = unique_list([int_or_badarg(fun type_to_int/1, Type)
  			 || Type <- UnsortedTypes]),
      encode_nxt_bmp(0, Types, <<>>).
  
  
negative.code: 
  round_pow(N, E) -> round(math:pow(N, E)).
  
  strip_leading_zeros(<<0, Rest/binary>>) ->
      strip_leading_zeros(Rest);
  strip_leading_zeros(Binary) -> Binary.
  