Reference Parameters in WSDL

In the editor's draft of the WSDL spec:

>> 4.3 Reference Parameters
>> 
>> The wsa:ReferenceParameters element (see Web Services Addressing 1.0 - 
Core[WS-Addressing-Core]) MAY be used as an extension child element of 
>> the wsdl20:endpoint or wsdl11:port elements. When present, the value of 
the [reference parameters] message addressing property for a message sent 
to an 
>> endpoint MUST match the contents of the wsa:ReferenceParameters 
extension element. If omitted, the value of the [reference parameters] 
message 
>> addressing property is empty.

The final sentence "If omitted, the value of the [reference parameters] 
message addressing property is empty."
appears to be restricting the addition of reference parameters unless they 
are explicitly defined by the WSDL.  I thought that the intention was to 
enable a mechanism to define reference parameters that the service 
requires, but not to restrict the sending of other reference parameters 
that are not defined by the WSDL. Have I mis-interpreted? 

Many thanks
Katy