I have this mapping:

<class name="Boss" table="Boss">
<id name="id" type="long" unsaved-value="null">
<generator class="identity"/>
</id>
<property name="name" type="string"/>
<joined-subclass name="BigBoss" table="BigBoss"/>
<key column="boss_id"/>
<property name="how_big"/>
</joined-subclass>
</class>

And these tables:

Boss
-----
id bigint (pk)
name varchar(70)

BigBoss
---------
boss_id bigint (reference id in Boss)
how_big varchar(50)

And I got this error :
SEVERE: Error parsing XML: XML InputStream(25) Element "joined-subclass" requires additional elements.
SEVERE: Error parsing XML: XML InputStream(26) Element "class" does not allow "key" here.
......
......


What did I do wrong?
Is it correct that element "key" in "joined-subclass" is a foreign key to the superclass?

remove the / from
<joined-subclass name="BigBoss" table="BigBoss"/>

Silly me. Thanks a lot!