A value expression. May be any string expression. If
      val_expr is an XML entity, a serialization of
      the entity is written to the stream. This is not
      the string value of the XML fragment, but a serialization of the XML
      fragment as text including all the markup, i.e. elements, attributes,
      namespaces, text nodes, etc. To get the string value of an XML entity,
      convert it to a varchat using cast. Casting as
      varchar will only produce a concatenation of the text nodes in the
      XML fragment, leaving out elements, attributes, name spaces, etc.