final sclass ConceptFieldIndexDesc<A extends Concept, Val> extends ConceptFieldIndexBase<A, Val> {
  *(Class<A> cc, S field) { super(cc, field); }
  *(Concepts concepts, Class<A> cc, S field) { super(concepts, cc, field); }
  
  void init {
    valueToObject = treeMultiSetMap(reverseOrder());
  }
  
  void register {
    concepts.addFieldIndex(cc, field, this);
  }
  
  public void close :: before {
    concepts.removeFieldIndex(cc, field, this);
  }
  
  synchronized L<A> objectsWithValueGreaterThan(O value) {
    SortedMap<O, Set<A>> subMap = ((SortedMap<O, Set<A>>) valueToObject.data).headMap(value);
    ret concatLists(values(subMap));
  }
}