Space is modem jargon for a binary
zero. In the days of the telegraph, Morse used an on/off one/zero code. Pens
at the receiving end made marks and spaces on a moving piece of paper. Sending a one
made a mark. Sending a zero made a space. Though we now use
ASCII (American Standard Code for Information Interchange), a simpler and less efficient code that Morse’s,
we still use the old terminology.