anchor.diff:      LB = url_param:to_list(B#sipurl.param_pairs),
   
       %% set vs ordset:
  -    %% ordsets is and retruns a sorted list, sets does _NOT_.
  -    %% ordsets should be better for for union, subtract and
  +    %% ordsets is and returns a sorted list, sets does _NOT_.
  +    %% ordsets should be better for union, subtract and
       %% intersection functions and as we do few insertions (only
       %% lists:usort/1 is run on the input to ordsets:from_list/1) there
       %% should be litle need for sets.
  
positive.code: 
  %% generate a escape hex encoding for a char
  escape(Char) ->
      [$\% | hex:to_hex_string(Char)].
  
       %%--------------------------------------------------------------------
       %% Function: url_is_equal(A,B)
       %%           A, B = sipurl record()
       %% Descrip.: return 'true' if A = B according to RFC 3261 chapter
       %%           19.1.4
       %% Returns : true | false
       %% Note    : assume that A and B are properly parsed sipurl records
       %%           with unencoded chars i.e. no hex encoded chars
       %%--------------------------------------------------------------------
       url_is_equal(A, B) when record(A, sipurl), record(B, sipurl) ->
  	    %% RFC 3261  - - - - - - - - - - - - - - - - - - - - - - - - - - -
  	    %% o  A SIP and SIPS URI are never equivalent.
  	    %% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  	    case A#sipurl.proto == B#sipurl.proto of
  		false ->
  		    false;
  		true ->
  		    url_is_equal_user_pass_host_port(A, B)
  	    end.
  
  url_is_equal_user_pass_host_port(A, B) ->
      %% RFC 3261  - - - - - - - - - - - - - - - - - - - - - - - - - - -
  
negative.code:     %% check that "name=val;;name=val" doesn't work
      io:format("test: is_parameters/1 - 8~n"),
      false = is_parameters("bar=Zo%3Dp%3dg;vaF=ghjT;;;BOF=tOp"),
      %% check that quoted parameters DON'T work, sipurl BNF does not allow quoted URI parameters
      io:format("test: is_parameters/1 - 9~n"),
      false = is_parameters("foo=\"bar\""),
  
      %% test new
      %%--------------------------------------------------------------------
  