That qed was done in the 1970s by Tom Duff, Hugh Redelmeier, David Tilbrook and myself. The regular expressions are from ed, plus simple forms of parentheses, alternation, and backreferences and a couple of minor tweaks that later appeared in vi.
It's essentially ed with some original qed features put back in, but with our spin. These include multiple files (buffers), string registers, and a couple of related commands. http://cm.bell-labs.com/cm/cs/who/dmr/qed.html -rob
