code: private boolean checkElementName(final Node node) {
          return TOPIC_INDEXTERM.matches(node)
                  || INDEXING_D_INDEX_SORT_AS.matches(node)
                  || INDEXING_D_INDEX_SEE.matches(node)
                  || INDEXING_D_INDEX_SEE_ALSO.matches(node);
      }
docs: Check if node is an index term element or specialization of one.
  
  @param node element to test
  @return {@code true} if node is an index term element, otherwise {@code false}