Similar to Figure 3, but showing the observed inclination damping efficiency (normalized by the expected value from Cresswell & Nelson 2008) vs. the observed gap depth. Values for the i-damping efficiency are shown for different inclinations i/h ∈ {0.25, 0.5, 1} by points of different colors joined together by opaque lines. The different panels are for different eccentricities, with e/h ∈ {0, 0.25, 0.5, 1}. Two dashed horizontal gray lines indicate, around the expected value in the limit of no gap (to the right in the plots), an error of 20%, which is the typical uncertainty of analytical planet–disk interaction formulas (Paardekooper et al. 2011). In all panels, there is a significant decrease in i-damping efficiency for deeper and deeper gaps, down to a factor of ∼1/5 less efficient damping at the transition from type-I to type-II regimes (gap depths of ≃0.3) as compared to the limit of no gap. The data are well modeled by a double-linear fit that depends on the gap depth, the eccentricity, and the inclination (see Equations (32) and (33)), shown with dashed lines of different colors depending on the orbital inclination.