Generally, the address of a user consists of:

• A user ID
• A system node, which is the ID of a computer system in a network

Often a person's user ID and system node are in the names directory of the Information Center Facility. When you know a person's address, you can send:

• Messages
  • Short messages to other users on your system node
  • Longer messages to users not necessarily on your system node
• Data sets, both entire data sets and members of a PDS