Analysing this Messiaen harmony

So, I've been over at oliviermessiaen.net, reading about his "chord on the dominant", a chord made up of all the notes in aa major scale, and, just to get this straight, in the 2nd example on oliviermessiaen.net - Messiaen's Chord and Harmonic Theory is the only thing connecting the different chords(or scales if you will) the C#/Db pedal note? Or this there another process at work here?