Do we really have to look these chords up in Forte's catalog in order to find a name for them? Another theorist [Christopher Hasty] assures us that, 'Allen Forte's perceptive interpretation...accounts for an essential quality of this mysteriously pulsating music. The eighth-note chords of the flute and clarinets form alternately, with the sustaining oboes and horns, the six-tone sonorities labeled A and B. The sonorities A and B are both representatives of the same set class (6-Z19) and are thus made up of precisely the same intervals. As Forte points out, "There is a flucuation of pitch-class content while interval content remains constant."' 'A fluctuation of pitch-class content while interval content remains constant' is what the rest of us have always known as 'a transposition.'