function _DataLen()
    {
        if (!isset($this->_data)) {
            return 0;
        }
        if (isset($this->_PPS_FILE)) {
            fseek($this->_PPS_FILE, 0);
            $stats = fstat($this->_PPS_FILE);
            return $stats[7];
        } else {
            return strlen($this->_data);
        }
    }