Serialism is an extension of Arnold Schoenberg's twelve-tone technique (sometimes called dodecaphony), which involves the use of tone rows: the basis of the system is that all the pitches used in a composition ultimately refer to a particular ordering (a "row") of one (and only one) instance of each of the twelve notes in the chromatic scale and permutations of that row. The composer either begins by creating a new row, or infers a row from free composition and attempts to structure the piece around that inference.