About the hook_ctools_plugin_api()

I am reviewing the coding of the module to see the structure of the module. I am not familiar with ctools and can see this module implements hook_ctools_plugin_api().

here is the code snippet:

/**
 * Implements hook_ctools_plugin_api().
 */
function msnf_ctools_plugin_api($owner, $api) {
  if ($owner == 'msnf' && $api == 'msnf') {
    return array('version' => 1);
  }
}

May I know what is the purpose of implementing this hook? It seems it is useless after I read the ctools documents.