A piece of performance art first described by Marcel Duchamp but later used by Fluxus artists, particularly Yoko Ono, Dick Higgins, Ken Friedman, Ben Patterson, George Brecht, Yasunao Tone, Nam June Paik and others. Usually consists of a set of instructions which may or may not be carried out by a performer, or the audience, or some combination thereof. The most famous book of such instruction pieces was published by Yoko Ono, called "Grapefruit". I saw a copy for sale in the Strand Bookstore one day and now regret that I didn't buy it on the spot.
Some Instruction Pieces from the book Grapefruit: