Level 1: the beaming shows three arpeggio domains. There is one passing tone.
Level 2, the passing tone is omitted, the domains are show as simultaneities. The middle domain functions as a link between the first and third domains. Passing tones lack stems and neighbor tones have stems.
Level 3: the middle domain is omitted because of its linking function and the remaining domains are consolidated into one simultaneity. The middle domain is considered a prolongation. Why?