    private function doctypeState() {
        /* Consume the next input character: */
        $this->char++;
        $char = $this->char();

        if(preg_match('/^[\t\n\x0b\x0c ]$/', $char)) {
            $this->state = 'beforeDoctypeName';

        } else {
            $this->char--;
            $this->state = 'beforeDoctypeName';
        }
    }
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.