Function:    LISTCTRL

Purpose:     Change and report Hermes' character output device state

Category:    SYSTEM, USER-INTERFACE 

File:        srvreq.c

Author:      J.P. Terlouw

Use:         INTEGER LISTCTRL ( NEW )

             LISTCTRL : device state prior to the call.
             NEW      : device state after the call. (INTEGER, input).
             
             The following device states are possible:
                0  both terminal and log file off;
                1  terminal on;
                2  log file on;
                3  both terminal and log file on.
             If an invalid (e.g. negative) device state is given,
             the function only reports the current device state.
             
             The NEW state is propagated to the tasks which activated the
             calling task (if any).
             
Examples:    Because the state is propagated to any caller task, this function 
             can be used to control output in a COLA script.
             This function can also be used to switch off unwanted terminal
             output which could be generated by a called subroutine over which
             the programmer has no control. 

Updates:     Jan  3, 1994: original document.