An application program can use the SENDCMD macroinstruction to issue VTAM® operator commands to VTAM and the RCVCMD macroinstruction to receive messages from VTAM. For a description of the SENDCMD macroinstruction, see SENDCMD—Send a VTAM operator command to VTAM. For a description of the RCVCMD macroinstruction, see RCVCMD—Receive a message from VTAM. Terminals in the network can be in session with any program operator, permitting VTAM commands to be entered from any terminal in the network either in this domain or in another.

If a program operator fails, VTAM reroutes to the system console any commands still outstanding that require a reply and any unsolicited VTAM messages. All other messages are discarded.

The program operator interface allows flexibility in controlling and managing the network. Careful planning is necessary to decide how much or how little programmed control to use.

The following steps describe a suggested approach to coding and developing a program operator:

1. Write a switching program that performs a minimum amount of VTAM operator control to permit an operator at a terminal in the network to enter commands and receive VTAM messages. This program (1) relieves the system console operator of a part of the responsibility for monitoring and controlling the VTAM network and (2) provides a base for further analysis and extension of network control.
2. Analyze the daily command procedures used by the operator at the terminal. Some of these procedures can be written into the program operator. For example, the operator might be entering a series of repetitive, time-consuming commands that can be handled by the program operator, or the replies to a series of commands can be summarized or handled by the program operator.
3. Change and extend the program operator or add program operators. New functions can be needed to aid the terminal operators or to support changes to the network configuration. The program can be expanded gradually until the desired amount of automatic operator control is implemented.
4. For a multiple-domain network, add application program-to-application program communication capability (between VTAM domains) to allow operator commands and replies to be exchanged between domains.