If you are running under

Field is set to

TSO or ISPF

The user TSO logon ID.

CICS

What the CA SYSVIEW CICS user ID exit routine passes back, or what the user enters on the user ID prompt screen. For a description of this exit, see the Administration Guide.

VTAM

What the user enters on the user ID prompt screen.

Batch interface

The batch jobs user ID.

API

The user ID of the user who invoked the API. If it is invoked under TSO, it is the user TSO logon ID. If it is invoked in a batch job, it is the user ID of the batch job.