ECP2/org.eclipse.emf.ecp.editor.controls.multireferenceviewer/plugin.xml

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.emf.ecp.editor.referencecontrols">
      <widget
            class="org.eclipse.emf.ecp.controls.multireference.ViewerMEControl"
            name="org.eclipse.emf.ecp.controls.multireference"
            showLabel="true"
            type="org.eclipse.emf.ecore.EObject">
      </widget>
   </extension>

</plugin>