    public function render($config) {
        $ret = '';
        $this->config =& $config;

        $this->def = $config->getHTMLDefinition();

        $ret .= $this->start('div', array('class' => 'HTMLPurifier_Printer'));

        $ret .= $this->renderDoctype();
        $ret .= $this->renderEnvironment();
        $ret .= $this->renderContentSets();
        $ret .= $this->renderInfo();

        $ret .= $this->end('div');

        return $ret;
    }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.