modify en:Code so that people can define new URIs that can be used.
Right now its just:

  <xs:simpleType name="EnumerationEndCodeType">
    <xs:restriction base="xs:anyURI">
      <xs:enumeration value=
        "http://www.w3.org/2009/09/ws-enu/SourceShuttingDown" />
      <xs:enumeration value=
        "http://www.w3.org/2009/09/ws-enu/SourceCancelling" />
    </xs:restriction>
  </xs:simpleType>

Proposal:
allow new (impl-specific URIs) to be used.
Change it to just an xs:any and let the body of the spec define the 
two well-known URIs.  

So "Code" would then change from:
<xs:element name="Code" type="tns:OpenEnumerationEndCodeType"/>

to:
<xs:element name="Code" type="xs:anyURI"/>