Any ideas as to what this TEXT_ERRROR_EZPAGES_ROBOT error is referring to?

Here's an excerpt from sitemapxml-ezpages.php that contains the above phrase, which I highlighter in red:

. $zen_SiteMapXML->base_url . '<br />', 'error');
$link = false;
} else {
if (basename($parse_url['path']) == 'index.php') {
$query_string = explode('&', str_replace('&amp;', '&', $parse_url['query']));
foreach($query_string as $query) {
list($parm_name, $parm_value) = explode('=', $query);
if ($parm_name == 'main_page') {
if (defined('ROBOTS_PAGES_TO_SKIP') && in_array($parm_value, explode(",", constant('ROBOTS_PAGES_TO_SKIP'))) || $parm_value == 'down_for_maintenance') {
$zen_SiteMapXML->message(sprintf(TEXT_ERRROR_EZPAGES_ROBOTS, $page_query->fields['alt_url'], $link) . '<br />', 'error');
$link = false;
break;