protected function _checkParts($value)
	{
		$value = (int) $value;

		if( $value < MShop_Order_Item_Base_Abstract::PARTS_NONE || $value > MShop_Order_Item_Base_Abstract::PARTS_ALL ) {
			throw new MShop_Order_Exception( sprintf( 'Flags "%1$s" not within allowed range', $value ) );
		}
	}