private boolean isAvailable() {
    if (!(myReference instanceof DefinitionReference) || !myReference.getElement().isValid()) {
      return false;
    } else {
      final RngGrammar grammar = ((DefinitionReference)myReference).getScope();
      if (grammar == null) {
        return false;
      } else if (grammar.getXmlTag() == null) {
        return false;
      }
      return true;
    }
  }
private boolean isAvailable()