Comparison of observations of the cometopause, collisionopause, ion-pileup boundary, and diamagnetic cavity boundary for three comet flybys as a function of production rate and distance from the comet. The predicted region for the ion-neutral (blue) and electron-neutral (red) collisionopause using Eq. (2) and the cross sections from Mendis et al. (1986) are also shown. Rosetta observations throughout the mission took place in the production and distance range covered by the gray box, and the boundary crossings are from Mandt et al. (2016). The lines for the flybys show the distances covered by the spacecraft.