code: private function checkForRoot($containedModel, $action)
      {
          if ($this->hasVariants() && $action == 'cut' && $containedModel->getProperty('varbase') == 0) {
              $this->disablePI = true;
          }
      }
docs: Check the PI for the root element.
  
  @param ModelInterface $containedModel The model with all data.
  
  @param string         $action         The action to be checked.
  
  @return void