Just intonation point
JIP (just intonation point), or commonly denoted "J", is a point in p-limit tuning space which represents untempered p-limit JI. Specifically, it is equal to ⟨log22 log23 log25 … log2p]. If M is a monzo, then <J|M> is M evaluated in terms of octaves. If we shift to weighted coordinates, so that M = [m2 m3 m5 … mp⟩ is represented by the ket vector [e2log22 e3log23 e5log25 … eplog2p⟩, then J becomes correspondingly the bra vector ⟨1 1 1 … 1].
As seen in the 5-limit projective tuning space diagram, it is the red hexagram in the center.