The XInclude definition is at http://www.w3.org/TR/xinclude/. This now has a namespace reference to http://www.w3.org/2001/XInclude and the http://www.w3.org/2003/XInclude reference is deprecated. The only real addition to or difference from the 2001 definition is the accept-charset attribute of element include. However, for immediate ease of use the 2003 namespace is retained in version 0.2 of the WMO19115 Community Core Profile - this physical instance document. It is referenced as ./XInclude.xsd in the version 0.2 WMO file list.