 The term can be applied to any classical music genre, as in "the standard operatic repertoire", "the standard symphonic repertoire" or "the standard piano repertoire"; referring to the pieces within that genre that fulfill said characteristics.As the standard repertoire is deeply rooted in the western classical music tradition, the pieces included respect the characteristics, complexity, and performance practice of classical music established during the common-practice period, although it is possible to find exceptions.Due to the "inflexibility" of the traditional techniques of composition and performance and the arduous and unclear requirements to enter the repertoire, a division has arisen between advocates of contemporary music and/or music outside the repertoire and those who promote and protect the founded tradition.