Piano: Ab 7sus2 in the Changes
Where Ab 7sus2 sits once the key is named, and what this seat is responsible for while it sounds.
Ab 7sus2 is Ab – Bb – Eb – Gb. Naming the notes is where a chord chart stops. A tune asks the next question instead, and that is the one this page answers.
Ab 7sus2 has no third of its own, so it names no degree until something around it does — which is why it turns up as a suspension over a chord that already has a job rather than as a chord with one.
The piano seat carries the whole harmony at once — a shell in the left hand, the colour tones and any substitution in the right, which is why this is the seat a substitution is usually heard from first. It is the only seat here that can state a chord and its substitute in the same beat, left hand holding one and right hand implying the other.
The diagrams are drawn across all 88 keys from A0 to C8, with the notes that sound lit and the ones a voicing drops shown dashed, so what you are looking at is a decision rather than a picture of every note in the chord.