screen

Ctrl-a q
Send a start signal (associated with Ctrl-q by terminals) to current window. (xon)

Ctrl-a s
Send a stop signal (associated with Ctrl-s by terminals) to current window. (xoff)

Ctrl-a Z
Reset virtual terminal to its "power-on" values. (reset)

http://www.oreillynet.com/linux/cmd/cmd.csp?path=s/screen