  It is observed that K-/pi in A+A and possibly p+p and pbar+p collisions
follows an interesting systematic in omega, the pion transverse energy per unit
of rapidity and transverse overlap area. The systematics show a linear increase
of K-/pi with omega in the AGS and SPS energy regime and a saturation at RHIC
energy. The systematics indicate that omega might be the relevant variable
underlying K-/pi. At high energy, the omega variable is related to the gluon
saturation scale in high density QCD, and perhaps to the initial energy density
in the Bjorken picture.
