Modern classical music is music written in the 20th century and beyond. Although much of it draws heavily on earlier forms, modern composers also experimented with rejection of long-held ideas; notably, Arnold Schoenberg questioned the traditional notions of harmony with his twelve-tone system[?], and John Cage questioned the very definition of music with his use of chance and found sounds.
... obligatory mechanisms controlling use in ways deemed by copyright holders to be unacceptable. See Professor Edward Felten's freedom-to-tinker Web site for information and ...