Multiple inheritence for content types?

Bioclipse is an environment for handling and processing life sciences data. This data is present in files with a wide variety of formats, each of which can contain a particular data type. For example, a we can have a single molecule in MDL molfile and in CML.

The latter is particularly interesting, as I do not know how to work that out... Firstly, I want the CML (Single Molecule) content type extend the CML content type, so that a validating CML editor can open it with the proper schema, but at the same time I would like to extend it a content type representation a Single Molecule. Hence, the multiple inheritance.

This is what the plugin.xml currently looks like:

<extension
  point="org.eclipse.core.runtime.contentTypes">

  <content-type
    base-type="net.bioclipse.contenttypes.cml"
    id="net.bioclipse.contenttypes.cml.singleMolecule2d"
    name="CML (Single 2D Molecule)"
    priority="high">
    <describer class="net.bioclipse.cml.contenttypes.CmlFileDescriber">
      <parameter
        name="dimension"
        value="2D"/>
      <parameter
        name="cardinality"
        value="single"/>
    </describer>
  </content-type>

</extension>

Very clearly, a single base-type. Is there any option of multiple inheritance?