Define a namespace for DataServiceVersion 4.0 following the OASIS conventions (http://docs.oasis-open.org/specGuidelines/ndr/namingDirectives.html#xml-namespaces):
http://docs.oasis-open.org/odata/ns/csdl/4.0
https://www.oasis-open.org/apps/org/workgroup/odata/download.php/46811/odata-csdl-v1.0-wd01-2012-09-03-RH.doc Accepted: https://www.oasis-open.org/apps/org/workgroup/odata/download.php/46918/latest/odata_meeting-7_on-20120913_minutes.html
OData currently uses the XML namespaces starting with http://schemas.microsoft.com/ado/