This is an early version of distributed unit of work that was first introduced in DB2 for OS/390 Version 2.2. It allows access to other DB2 UDB for z/OS subsystems using a communications method that is private to DB2 UDB for z/OS. With this method you can connect to one location and run one query per unit of work. DB2 UDB for z/OS-to-DB2 UDB for z/OS distributed unit of work uses an alias or a three-part name to determine the location of the subsystem and to connect to it. The figure below shows a DB2 UDB for z/OS-to-DB2 UDB for z/OS access connection.