Note: Because of the large size of this score, it is shipped rolled in a tube.
Klavierstück XI is famous for its mobile, or polyvalent structure. The mobile structure and graphic layout of the piece resembles that of Morton Feldman's Intermission 6 for 1 or 2 pianos of 1953, in which 15 fragments are distributed on a single page of music with the instruction: "Composition begins with any sound and proceeds to the any other". in the same year, Earle Brown had composed Twenty-five Pages for 1–25 pianists, in which the pages are to be arranged in a sequence chosen by the performer(s), and each page may be performed either side up and events within each two-line system may be read as either treble or bass clef. When David Tudor, who at the time was preparing a version of Feldman's piece, was in Cologne in 1955, Stockhausen asked him,
"What if I wrote a piece where you could decide where you wanted to go on the page?" I said I knew someone who was already doing one, and he said, "In that case I shall not compose it". So I retracted, and said it was just an idea my friend was thinking about, and told him he mustn't consider any other composer but should go ahead and do it anyway, and that led to Klavierstück No. 11.
Apart from the layout on the page, Feldman's piece has nothing in common with Stockhausen's composition. Rather than rhythmic cells, its components are single tones and chords, with no rhythmic or dynamic indications.
Klavierstück XI consists of 19 fragments spread over a single, large page. The performer may begin with any fragment, and continue to any other, proceeding through the labyrinth until a fragment has been reached for the third time, when the performance ends. Markings for tempo, dynamics, etc. at the end of each fragment are to be applied to the next fragment. Though composed with a complex serial plan, the pitches have nothing to do with twelve-tone technique but instead are derived from the proportions of the previously composed rhythms.