[pmwiki-users] What is "dc"?

[JB]

From: http://www.pmwiki.org/wiki/PmWiki/WebFeeds

   if ($action == 'rss') include_once('scripts/feeds.php');
   if ($action == 'atom') include_once('scripts/feeds.php');
   if ($action == 'rdf') include_once('scripts/feeds.php');
   if ($action == 'dc') include_once('scripts/feeds.php');


I know what rss, atom , rdf are.  What is "dc"?