Resolution: BW does not produce SOAP messages with multi-references generally.
Example: <Car href="#somecar" />
A multi-reference accessor is used in RPC/Encoding style. How an encoding schema for the SOAP data model may be applied to XML Schema definitions is not clearly specified. Neither the SOAP specification (which defines SOAP encoding) nor the WSDL specification (which applies it to XML schema definitions) answers this question. As it is not specified, BW's implementation is to process this kind of message but will not produce it.