This specifies the directory service to be managed.

     DIRECTORY_SERVICE dir-service

 The service must be one of:

     DIRECTORY_SERVICE DECDNS

 The Local and Phase IV databases do not require any directory service
 management functions.  This command does not apply to these directory
 services.

 If not specified, the default service type is used.  This default can be
 displayed or changed using the SHOW or SET DEFAULT commands.