<model>
  <class name="Memo" role="Summary">
    <attributes>
      <attribute name="contents" type="Text" isKey="F" />
      <attribute name="attachment" type="URL" mult="0..*" isKey="F"/>
      <attribute name="totalAmount" type="Number" />
    </attributes>
  </class>
  <class name="LineItem">
    
  </class>
  <class name="Product">
    
  </class>
    <class name="DigitalProduct">
    
  </class>
  <relationship type="Association">
    <source class="Lesson" multiplicity="0..*" />
    <target class="LearningAsset" multiplicity="1..*" />
    <label text="-uses">
  </relationship>
  <relationship type="Generalization">
    <source class="DigitalProduct" />
    <target class="Product" />

  </relationship>
</model>
