class tag problem: If I remove that then the the mapping is loaded fine, so I guess the class tag is fine. Position: I am not sure, I will try and read some more. Does anyone have any ideas how to read this error org.xml.sax.SAXParseException: The content of element type "class" must match "(meta*,(cache|jcs-cache)?,(id|composite-id),discriminator?,(version|timestamp)?,(property|many-to-one|one-to-one|component|dynamic-component|any|map|set|list|bag|idbag|array|primitive-array)*,(subclass*|joined-subclass*))". I mean what does these characters mean: ...