protected function renderDoctype()
    {
        $doctype = $this->def->doctype;
        $ret = '';
        $ret .= $this->start('table');
        $ret .= $this->element('caption', 'Doctype');
        $ret .= $this->row('Name', $doctype->name);
        $ret .= $this->row('XML', $doctype->xml ? 'Yes' : 'No');
        $ret .= $this->row('Default Modules', implode($doctype->modules, ', '));
        $ret .= $this->row('Default Tidy Modules', implode($doctype->tidyModules, ', '));
        $ret .= $this->end('table');
        return $ret;
    }