<class [b]name="A"[/b] table="[b]tableA[/b]" discriminator-value="0" [b]entity-name="A"[/b]>
  <id name="id" unsaved-value="null" type="int">
    <generator class="native"/>
  </id>
  <discriminator column="someid" type="int" />
  <property name="..." />
  ...
  <subclass [b]entity-name="AA"[/b] [b]name="AA"[/b] discriminator-value="1">
  </subclass>

  <subclass entity-name="AB" name="AB" discriminator-value="2">
  </subclass>
  ....
</class>


<class [b]name="A"[/b] table="[b]tableB[/b]" discriminator-value="0" [b]entity-name="order_A"[/b]>
  <id name="id" unsaved-value="null" type="int">
    <generator class="native"/>
  </id>
  <discriminator column="someid" type="int" />
  <property name="..." />
  ...
  <subclass [b]entity-name="order_AA"[/b] [b]name="AA"[/b] discriminator-value="1">
  </subclass>
  <subclass entity-name="order_AB" name="AB" discriminator-value="2">
  </subclass>
  ....
</class>




<class name="Z1" table="tableZ1">
   ....
   <set name="someset" ... [b]cascade="save-update"[/b]>
      ...
      <many-to-many column="..." entity-name="A"/>
   </set>
   ...
</class>

<class name="Z2" table="tableZ2">
   ....
   <set name="someset" ... [b]cascade="save-update"[/b]>
      ...
      <many-to-many column="..." entity-name="order_A"/>
   </set>
   ...
</class>


class Z1 {
   Set<A> someset;
}

class Z2 {
   Set<A> someset;
}

class A { ... }
class AA extend A { ... }
class AB extend A { ... }