Line mode TSO/E is the way programmers originally communicated interactively with the MVS™ operating system. They issued TSO/E commands and entered text at the terminal one line at a time rather than from panels.

You can still use line mode TSO/E to communicate with the MVS system. To use line mode TSO/E, enter a command after the READY message is displayed. The READY message indicates that you are in line mode TSO/E.

When you are in either ISPF/PDF or the Information Center Facility, you need only press the RETURN PF key (PF 4) or press the END PF key (PF 3) repeatedly until you see the READY message.