(UNIX only)  When ON, the ^S and ^Q keys can be used to stop and start rapidly scrolling output (such as from a TYPE or DIR command) as long as the program is not waiting for input, and as long as the current line handshaking discipline supports XON/XOFF. In most cases, while waiting for keyboard input, XON/XOFF is disabled to avoid conflicts with other uses of these keys. (One exception is VUE. In order to access the ^Q and ^S VUE commands, you can use the alternate sequences ^_Q and ^_S.) When XONXOFF=OFF, the ^S and ^Q keys do not do anything special.

XONXOFF=ALWAYS is like ON, except that it leaves XON/XOFF control active even during input operations. This takes away the ability to use ^S and ^Q as input commands, but it eliminates a problem which can happen with some dumb terminals in which the turning off of flow control during the transition from a long output to an input can cause the last few characters of the previous output operation, which had been output by A-Shell but were still buffered by the operating system, to become garbled. The symptom of this problem could be seen in a long DIR/W operation, in which it would handshake correctly up until the last couple of lines at the end, just before returning to the dot prompt.

In most cases, the PAGE.LIT command will accomplish the same thing (only better) for which you were trying to use Ctrl+S and Ctrl+Q.