Seems kind of like Zwrite: text-only, ephemeral messages. It was just text that appeared in your terminal session. My friends and I used it in (engineering) grad school in the late 90's.

Good god, there's still a manual online: http://web.stanford.edu/group/privacyproject/currentStateUni...

"They have no control over what text the message replaces, but can always press the key combination control-L to restore their screen."