Earlier quoted context omitted.
This reminder of undocumented behavior reminded me of The story of Mel, a Real Programmer. See http://www.pbm.com/~lindahl/mel.html
I'd never seen that photo before. Mel looks a bit like Brad Pitt from far away.
Until very recently, I assumed the story was mostly apocryphal, but I happened to look it up about a year ago and learned that the actual Mel had been identified, and that there was even that picture. Really cool, considering I first saw the story of Mel in probably 1989.