Mutable entities should be creatable as well as deletable. The difficulty with immutable and checking for changes (to see whether we should throw an exception) is that of performance in the case of simple reattachment of detached entities. This is less an issue in the case of merge()/saveOrUpdateCopy(). But in the simple case reattachment this would require a select to know the previous values. So for consistency-sake (I assume) immutable="true" always just ignores any potential changes. We could certainly add a feature for the optional ability to perform the checking (which I agree would be more desirable, probably, as a user). -- Steve Ebersole Project Lead http://hibernate.org steve(a)hibernate.org Principal Software Engineer JBoss, a division of Red Hat http://jboss.com http://redhat.com steve.ebersole(a)jboss.com steve.ebersole(a)redhat.com On Tue, 2008-06-24 at 13:05 +0200, Hardy Ferentschik wrote: