It is quite literal. It looks at the pitches which are overlapping and counts up from the bottom starting at zero. One gotcha with this is if you have two adjacent chords that both use the same pitch for a note sustained across both chords. That note will be counted on the first chord and skipped on the second as the note is seen as part of the first chord. I usually have zero to a few of these and just correct by hand.
It’s not really a preset, instead it is just one of the selection elements in the LE. Attached is an example that will select the top note (aka 4th lowest) in 4-note chords - notice it is using 3 & not 4.
