WebDAV cannot be validated by schema, since an implementation must be able to ignore elements it does not understand. (RFC 4918: "A recipient of a WebDAV messa

WebDAV cannot be validated by schema, since an implementation must be able to ignore elements it does not understand. (RFC 4918: "A recipient of a WebDAV message with an XML body MUST NOT validate the XML document according to any hard-coded or dynamically-declared DTD.")