While JDO2+ allows specification of embedded objects stored with primary objects, it doesn't have any specific way of specifying the embedded object as being inherited and how you would persist it. In particular there is no way to define a discriminator (column) for the embedded object. If we have an example from the JDO spec, and if we have a subclass of Address as also persistable, then we need to specify the discriminator for "primaryAddress" field.
<class name="Employee" table="EMP">
<!-- field type is Address -->
<field name="street" column="PADDR_STREET"/>
<field name="city" column="PADDR_CITY"/>
<field name="state" column="PADDR_STATE"/>
<field name="zip" column="PADDR_ZIPCODE"/>
So the XSD/DTD need updates to allow <discriminator> under <embedded>, the JDO Metadata API needs to allow this also, and the @Embedded annotation needs a "discriminator" attribute adding.