Alois Hába, Suite für vier Posaunen, Mvt. II, Andante cantabile, mm. 23-25
The final three measures of the second movement prolong an A-flat major triad, although the role of the F-quarter-sharp is ambiguous. Is it a passing note that divides the perfect fourth A-flat to E-flat into two equal segments? Or is it a part of an arpeggiation of some kind of A-flat chord with an added quarter-tone sixth?