This function adds a node registration to a directory service, or modifies
 a current node registration.

 When the node name is entered, it is checked to see if it already exists
 in the directory service.  If it does not yet exist, a message is
 displayed indicating that a new node is being registered.  This feature
 is used when a new node is made available in the network, and the node
 registration needs to be added to a directory service to allow lookup by
 other nodes.

 If the node name already exists, a message is displayed indicating that
 the node name is being modified, and the currently registered values are
 read and presented as inout defaults.

1  –  Directory Service

 This field specifies the directory service that contains the node
 registration to be shown.  The service must be one of:

     LOCAL
     DECDNS
     PHASEIV

 The service type can be abbreviated, as long as the abbreviation is
 unique.

2  –  Node Name

 This field specifies the name of the nodes to be registered or modified.
 This must be the fully specified name for the node in the directory
 service.

 The syntax of a fully specified name depends on the directory service
 being used.  Examples of fully specified names might be:

     For Local:      MailHub
     For DECdns:     MyCo:.Sales.MailHub
     For Phase IV:   MLHUB

3  –  Synonym

 This field specifies the Phase IV synonym for the node.  Phase IV
 synonyms can be used in place of fully specified node names,
 particularly with applications that do not support full node names.

 The synonym must be from 1 to 6 letters (A to Z) or digits (0 to 9),
 with at least one letter.  If the field is left blank, a synonym name
 is not registered for the node.

4  –  Address Towers

 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.