Alban Berg’s Violin Concerto (1935) ends with a “tonic triad of B flat, with added sixth [that] follows a harmonic progression found frequently in 1930s dance-band arrangements.” However, Richard Taruskin points out that Berg's "chord thus created, B flat, D, F, G had an important poetic resonance", as it echoes the ending of Mahler's "Abschied." Stravinsky’s "Symphony in Three Movements" (1945) “incorporates elements of American popular music, most famously the final chord, a Hollywood added-sixth chord of ever there was one.”  (Stravinsky himself later criticized his choice of the final D sixth chord as ‘commercial.’ ) Messiaen’s “Louange à l’immortalité de Jésus”, the final movement of his "Quartet for the End of Time" (1941) opens with a meditative theme “played entirely over a 6-4 chord with added sixth”   The "Neapolitan sixth" is the first inversion of a major triad built on the flattened supertonic (second degree of the scale) – a Neapolitan sixth in C major, therefore, consists of the notes F, A, and D. There are a number of "augmented sixth" chords. Each of them has a major third and augmented sixth above the bass. When these are the only three notes present, the chord is an "Italian sixth"; when an augmented fourth is added above the bass, the chord is a "French sixth"; while adding a perfect fifth above the bass of an Italian sixth makes it a "German sixth" (the etymology of all these names is unclear). All usually have the (sixth degree of the scale, A in C major, for example) as the bass note – in this case, they tend to resolve to the dominant. The sixth factor of a chord is six scale degrees above the root. Conventionally, the sixth is third in importance to the root, fifth, and third, being an added tone. It is generally not allowed as the root since that inversion resembles a seventh chord on the sixth rather than an added tone on the original note. In jazz chords and theory, the sixth is required due to it being an added tone. The quality of the sixth may be determined by the scale or may be indicated.