Logical terminals (LTERMs)

A logical terminal (LTERM) is a user destination. For statically defined terminals, each LTERM is associated with a physical terminal. For ETO terminals, each LTERM is associated with a user, and is associated with a physical terminal only after a user has signed on to a physical terminal.

Each logical terminal has an installation-defined name, called the LTERM name.

Reserve one LTERM and identify it as the IMS master terminal. This logical terminal is the control point for the online IMS. Commands associated with this LTERM start and stop the system, control the system resources, and display the status of those resources. The master terminal operator (MTO) can use the /ASSIGN command to alter the physical device that is associated with the LTERM. When ETO users sign on, altering the physical device that is associated with the LTERM is automatic. The device is identified by either the node name or the line number with the physical terminal identifier.

When a user enters a transaction, the logical terminal name is associated with the input message, and input messages are queued by transaction code. The output message queue designation is actually the LTERM name itself. Although this name is often the same for output as for input, an application program can cause the output to be directed to an alternate LTERM. An input terminal can also specify an LTERM name as the destination of a message. A message switching (input) edit routine can append the current input LTERM name to the message.