public function addRevisionHistory($text, $revision, $start, $end, $class, $source = null)
    {
        
        $text  = $text . $start;
        $text .= "<ul class=\"$class\">\n";
        
        foreach ($revision as $date => $info) {
            $text .= "<li>$date: $info</li>\n";
        }

        $text .= "</ul>\n";

        if ($source) {
            $text .= "<p><a class=\"$class\" href=\"$source\">"
            . t("Document source")
            . "</a>.</p>\n";
        }

        $text .= $end;

        return $text;
    }