The piece consists of 20 single, unnumbered pages, plus title page with performance instructions. The 20 pages may be used in whole or in part by 1 to 20 pianists. The performer(s) make(s) a program of a determined timelength and translate(s) this to the page(s) to be played (space=time). Every page contains five syswtems, notated on five bars. Some pages contain very few events (one of them evern just one!), while others are more or less ""filled up"". Most events are aggregates of notes, to be played as a single ictus. Dynamics, resonances, overlappings, and interpenetrations are free. The composition means involved both chance operations and observation of imperfections in the paper upon which the music was written. The work may be performed with ""Atlas Eclipticalis"" and with ""Song Books"".

Composer: Cage, John