I noticed that a Drupal core function is using the following code:
$categories = db_select('contact', 'c') ->addTag('translatable') ->fields('c', array('cid', 'category', 'recipients', 'selected')) ->orderBy('weight') ->orderBy('category') ->execute() ->fetchAll();
When should a module add that tag to the query it is executing?
What is the effect of adding that tag? What is effectively altered, in the query object, or in the result returned by the query?