Its definitely required for the previous javaee descriptors where there are multiple versions, so I don't see this as much of a requirement. The reason the simple persistence key is not working is that when the PersistenceMetaData is resolved, its jaxb @XmlRootElement declares a namespace that does not match the empty namespace used by the descriptor. In general proper namespaces are needed. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4157218#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...