Specifies how to rewrite the source NSAP. Digits will be set directly to the new NSAP. A '.' will move a digit from the old NSAP to the new NSAP. A '*' will move all remaining digits from the old NSAP to the new NSAP. A '%' will delete a digit from the old NSAP. A '#' will append all digits from the old NSAP to the new NSAP. Please note that the eventually leading '@' (indicating extended adressing) is handled execatly like digits. If this object is empty, the source NSAP will not be changed.