Editing In C (section)

===Instructions===
There are a few rules for performing ''In C'' that have remained since its first performance. They primarily define the [[Indeterminacy (music)|indeterminacy]] of the piece:
*'''Instrumentation''': The piece can be played by any group of musicians on any type of instrument.
*'''Tempo''': There is no required tempo. All performers play at the same pace.
*'''Patterns''': The 53 patterns are to be played in order. 
*'''Repetitions''': Individual players determine how often to repeat any pattern.
*'''Transposition''': Patterns may be transposed up or down. 
*'''Coordination''': An 8th note pulse may be used to coordinate the performance. It can be played on the top two octaves of a piano or mallet percussion. Time can also be kept by improvised percussion.
*'''Ending''': The piece ends when all players arrive at pattern 53. Performers stop playing individually.<ref name=Riley05/>

[[File:Module 12 from Terry Riley's "In C".png|thumb|Terry Riley's diagram of potential alignments for module 12 from ''In C''.<ref name=Turek/>|left]]Riley suggests a group of about three dozen performers, while acknowledging smaller and larger groups are possible.<ref name=Riley05>Riley, Terry. [https://issuu.com/scoresondemand/docs/in_c_-_00lead_part_x1 ''In C'']. [[Associated Music Publishers]], 2005.</ref> Though they are governed by the same tempo, the musicians are not required to play together. Performers are encouraged to stagger their entrances, which creates a [[Heterophony|heterophonic]] [[Canon (music)|canon]]. Riley diagrammed the 12th module in several alignments to demonstrate how freely the musicians can perform the score. He initially asked players to remain within 4–5 modules of each other.<ref name=Turek/> The current instructions reduce that bandwidth to 2–3 patterns. Riley also recommends coalescing in [[unison]] at some point.<ref name=Riley05/> 

If one of the motifs is too difficult to play, a performer is allowed to omit it. Riley even allows for the rhythms of patterns to be augmented. 

''In C'' has elements of [[aleatoric music]] due to its improvisatory nature.<ref>Honigmann, David. "[https://web.archive.org/web/20160924021518/https://www.ft.com/content/8959b73a-2f30-11e3-ae87-00144feab7de#axzz38lf7q1Lq In C, Barbican, London – review]". ''[[Financial Times]]'', October 7, 2013.</ref> However, much of its structure is specifically designed to reduce the scope of chance.<ref>Bernard, Jonathan W. "The Minimalist Aesthetic in the Plastic Arts and in Music." ''[[Perspectives of New Music]]'', vol. 31, no. 1, 1993. 96. https://doi.org/10.2307/833043.</ref> Riley conceived of a version where each pattern lasted a week and the final pattern was played in the new year.<ref name=Turek/> He estimates an average run time of 45–90 minutes.<ref name=Riley05/> His instructions avoid declarative statements and read like a series of helpful suggestions. Riley composed the piece to deliberately have "a lot of liberties".<ref name=Alburger/>{{rp|9}}