(UNIX only) This is a rather weird option that was implemented to overcome some kind of shortcoming in the AS400 implementation of Telnet, and would only apply (if then) in a situation where AS400 users were connecting via Telnet to A-Shell running on a UNIX machine. The problem was that when the user typed too fast, bursts of Backspace and other control characters would mysteriously be dumped into the input buffer. With this option turned on, A-Shell filters those characters out.