anchor.diff:  %%           component is already present in Params
   %%--------------------------------------------------------------------
   to_norm(Params) when is_list(Params) ->
  -    F = fun({Name, Val}) ->
  -		{ httpd_util:to_lower(Name),
  -		  case Val of
  -			[$\" | _] -> Val;  %% quoted value, don't lowercase
  -			_ -> httpd_util:to_lower(Val)
  -		  end
  -		}
  +    F = fun({Name, ValIn}) ->
  +		Val =
  +		    case ValIn of
  +			none ->
  +			    none;
  +			[] ->
  +			    none;
  +			[$\" | _] ->
  +			    ValIn;  %% quoted value, don't lowercase
  +			_ when is_list(ValIn) ->
  +			    httpd_util:to_lower(ValIn)
  +	            end,
  +		{ httpd_util:to_lower(Name), Val}
   	end,
       %% make case insensitive
       L = [F(E) || E <- Params],
  
positive.code: %%--------------------------------------------------------------------
  %% Include files
  %%--------------------------------------------------------------------
  
  -include("siprecords.hrl").
  
  %%--------------------------------------------------------------------
  
negative.code: %%--------------------------------------------------------------------
  %% Function: to_norm(Params)
  %%           Params = list() of {Name, Val}
  %%           Name = string(), treated as case insensitive
  %%           Val  = string() | none, treated as case insensitive
  %%                                   unless it starts with a quote
  %% Descrip.: convert a contact-parameter list to a normalized (a case
  %%           insensitive form) form
  %% Returns : contact_param record() |
  