anchor.diff:      %% throw exception if whole string doesn't match
       {match, 1, HostL} = R,
       Host.
  -    
  -	
  +
  +
   %%--------------------------------------------------------------------
   %% Function: is_IPv4address(Str)
   %%           Str = string(), the host string
  -%% Descrip.: parse host string, throw a exception if it doesn't 
  -%%           conform to the format specified in RFC3261 chapter 25.1 
  -%%           p218
  +%% Descrip.: parse host string, throw an exception if it doesn't
  +%%           conform to the format specified in RFC3261 chapter 25.1
  +%%           page 218
   %% Returns : Str | throw()
   %% Note    : this function only matches IPv4 hostnames
   %%--------------------------------------------------------------------
  
positive.code: 	{error, _Reason} -> throw({error, not_a_IPv6_reference})
      end.
  
  %%--------------------------------------------------------------------
  %% Function: 
  %% Descrip.: autotest callback
  %% Returns : 
  %%--------------------------------------------------------------------
  test() ->
      %% split_fields/2
      %%--------------------------------------------------------------------
      %% test regular case
      io:format("test: split_fields/2 - 1~n"),
      {"foo", "bar"} = sipparse_util:split_fields("foo@bar", $@), 
      %% test missplaced Separator
      io:format("test: split_fields/2 - 2~n"),
      case catch sipparse_util:split_fields("@bar", $@) of
  
negative.code: 	    ($_, Acc) -> Acc;
  	    ($+, Acc) -> Acc;
  	    ($`, Acc) -> Acc;
  	    ($\', Acc) -> Acc;
  	    ($~, Acc) -> Acc;
  	    (Char, Acc) ->
  		Acc and is_alphanum(Char)
  	end,
      lists:foldl(F,true,Str).
  
  
  %%--------------------------------------------------------------------
  %% Function: is_hostname(Str)
  %%           Str = string(), the host string
  %% Descrip.: parse host string, throw a exception if it doesn't
  %%           conform to the format specified in RFC3261 chapter 25.1
  %%           p218
  %% Returns : Str | throw()
  %% Note    : this function only matches symbolic hostnames
  