Function Keys Supported under BS2000

This document describes the Natural function-key assignments that are supported for terminal devices of the 975n series (types 974n, 975n and 976n).

Key Assignment

In Natural, function keys serve to transfer data together with specific command/execution information to a program.

For terminal device types that only support the keys F1 to F5, the programmable P keys (P1 to P20) are used for this purpose. This means that these keys are assigned the function key values PF1 to PF20 (in 3270 terminology).

The identification of the key pressed is made from Natural-loaded key assignments in connection with the send-key code F5. This allows the distinction of similar data types which were sent using DUE1. Using F5, Natural recognizes the function-key resolution and interprets the P-key value as a code. In the other instance the data are transferred to the executing program.

The loading of keys is controlled by terminal commands or from the executing program using SET CONTROL statements.

Modes for Key Assignment

There are three types of modes for key assignment:

Mode Description
KN For terminal types 974n, 9750 - 9755, the literals %K1 to %K20 are assigned to the keys (terminal command %KN or statement SET CONTROL 'KN').

For terminal types 9756, 9758, 976n, send-key codes F1 to F20 are loaded to the keys P1 to P20.

KO The literals 01 to 20 and the send-key code F5 are assigned to the keys (terminal command %KO or statement SET CONTROL 'KO').
KS The literals A to T as well as the send-key code F5 are assigned to the keys (terminal command %KS or statement SET CONTROL 'KS').

In KS mode, a dummy field is generated in the last two terminal positions of each output message. This field is used for receiving and transferring the key value. Prior to data transfer the cursor is moved in this field using the movement functions assigned to the keys.

If an N is specified after the respective terminal command (that is, %KNN, %KON or %KSN), only the corresponding function-key mode is activated, but no values are loaded to the P keys.

For all modes, cursor-position-dependent key processing, according to current assignment, can lead to differing results. For example, the help key, dependent on field assignment, can invoke either the global or local help processing for a particular field. Such functions should be controlled using PF21 to PF23 interpreted keys (F1 to F3).