Rotation-activity diagram as in Fig. 11c, but now displaying different possible models for the rotation-activity relationship. The orange lines show classical segmented power law fits with a constant saturated regime, while green lines show power law fits with a slope in the saturated regime. The solid (green and orange) lines have a fixed break point at Ro/Ro_⊙0 = 0.1, while it is a free model parameter for the models shown with the dashed lines. The blue line shows the linear-logarithmic model. It is remarkable that a 2-parameter fit can come closest to describing the X-ray behaviour of such a wide range of stars. Both panels show the same content, logarithmic with Ro/Ro_⊙ (left) and linear with Ro/Ro_⊙ (right). For clarity, we do not show the fits to the unsaturated regime alone.