<Dl> <Dd> Main article: Combinatoriality </Dd> </Dl> <Dd> Main article: Combinatoriality </Dd> <P> Combinatoriality is a side - effect of derived rows where combining different segments or sets such that the pitch class content of the result fulfills certain criteria, usually the combination of hexachords which complete the full chromatic . </P> <P> Invariant formations are also the side effect of derived rows where a segment of a set remains similar or the same under transformation . These may be used as "pivots" between set forms, sometimes used by Anton Webern and Arnold Schoenberg . </P>

Which of the following is not a form that a tone row can appear in a twelve tone composition