message listCandidateResourcesRequest
parts 
parameters
element dir:listCandidateResources
used by 
Operation listCandidateResources in PortType DirectoryService
source  
<wsdl:message name="listCandidateResourcesRequest">
  <wsdl:part name="parameters" element="dir:listCandidateResources"/>
</wsdl:message>

WSDL documentation generated by XMLSpy WSDL Editor http://www.altova.com/xmlspy