The tap code, sometimes called the knock code, is a way to encode messages, letter by letter, in a very simple way and transmit it using a series of tap sounds, hence its name. It has been commonly used by prisoners to communicate with each other. The method of communicating is usually by "tapping" either the metal bars, pipes or the walls inside the cell.
Famous quotes containing the words tap and/or code:
“Anna who was mad,
I have a knife in my armpit.
When I stand on tiptoe I tap out messages.”
—Anne Sexton (1928–1974)
“Acknowledge your will and speak to us all, “This alone is what I will to be!” Hang your own penal code up above you: we want to be its enforcers!”
—Friedrich Nietzsche (1844–1900)