This field allows you to indicate how you want to handle the address
 towers for the node registration.  You can enter one of the following
 keywords.  These can be abbreviated, as long as the abbreviation is
 unique.

   Modify    - Modify the current address towers.

               If the node is being registered, this allows you to enter
               new address towers.

               If the node is being modified, the old towers are presented
               as defaults, and you can change, add, or delete address
               tower information.

   Keep      - Keep the current address towers.

               If the node is being registered, it has no current towers.
               Use this to indicate that no towers are to be registered
               for the node.

               If the node is being modified, the current address towers
               remain unchanged.

   Replace   - Replace the current address towers.

               If the node is being registered, this allows you to enter
               new address towers (this is equivalent to modify).

               If the node is being modified, the current towers are
               deleted, and you are asked for a new set of towers to be
               registered for the node.

   Delete    - Delete the current address towers.

               If the node is being registered, it has no current towers.
               This indicates that no towers are to be registered for
               the node (this is equivalent to keep).

               If the node is being modified, the current towers are
               deleted.  You are not asked for a new set of towers.

 If you answer replace or modify, another form is brought up to allow
 you to enter the address tower information.

 If you answer keep or delete, you are asked if the node should be
 registered or modified.  You can proceed or cancel the operation at
 this time.