Guide Tones I

The Guide Tones I voicing of Abmb6 stacks Cb and Fb from the bottom up: the minor 3rd and flat 6th of the chord. It leaves out the root, Ab, for the left hand or the bass player to take.

It's one of the Guide Tones voicings: just the 3rd and 7th, the notes that define each chord, played over the root. The other for Abmb6 is Guide Tones II.