Bars per hyperbar. Falls back to the span's own bar count when the span is too short to hold two of any candidate grouping.
Absolute beat of each hypermetric downbeat inside the analysed span, in time order. A pickup bar is not a group head, so the first entry is the first full bar that starts a group.
How much the music supports the grouping, in [0, 1]: how strongly harmonic change and cadences prefer these bars over the others, discounted when the runner-up grouping explains the music nearly as well.
Why this grouping was chosen.
A bar grouping inferred from the music.