Long strip of stiff cardboard made of separate pieces glued together in two staggered layers (like two rows of bricks), and folded in zig-zag fashion into a compact pile or "book." Music is scored lengthwise on the book by rectangular or round perforations. Book music is usually played on a key frame or a keyless frame (also listed in this Glossary). Most very large band organs and dance organs use cardboard music because books are generally less susceptible to tracking problems than music rolls. * Synonyms: cardboard music, music book. * French: carton. * German: Kartonnoten.