    public function __construct() {
        $this->p_start  = new HTMLPurifier_Token_Start('', array());
        $this->p_end    = new HTMLPurifier_Token_End('');
        $this->p_empty  = new HTMLPurifier_Token_Empty('', array());
        $this->p_text   = new HTMLPurifier_Token_Text('');
        $this->p_comment= new HTMLPurifier_Token_Comment('');
    }
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.