Mapping for unidirectional association sample

gistfile1.xml

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHTests" namespace="NHTests">
  <class name="Order" table="Orders">
    <id name="Id">
      <generator class="guid" />
    </id>
    <version name="Version" />
    <property name="OrderTime" />
    <bag name="OrderLines" cascade="all-delete-orphan" >
      <key column="OrderId" />
      <one-to-many class="OrderLine" />
    </bag>
  </class>

  <class name="OrderLine" table="OrderLines" >
    <id name="Id">
      <generator class="guid" />
    </id>
    <property name="ProductName" />
    <property name="Price" />
    <property name="Quantity" />
  </class>
</hibernate-mapping>