Rotation–chromospheric activity relation divided into four parts according to the “CgIW” scenario. The solid vertical lines indicate the critical points between the C, gap, and I regions (Ro ≈ 0.022 and Ro ≈ 0.15, respectively). The dashed vertical line marks the transition to the weakened-magnetic-braking phase at Ro≈0.7. The green lines represent the best fit of our proposed model and yellow lines represent the best fit of the dichotomy model. The 1σ scatter and 2σ scatter of the fit are indicated by the shaded gray region. The location of the Sun is marked with an ⊙ symbol. Representative error bars are plotted for the datapoints in the C region.