Four sets of fiducial data (M ± δM, R_eq ± δR_eq) placed in the mass-radius relationship for IW planets (left panels) for M = 1M_⊕, and R_eq = 1.3 R_⊕ (top) and R_eq = 0.85 R_⊕ (bottom). Error bars are δM/M = 0.1 and δR_eq/R_eq = 0.02 (black, plain lines) and δM/M = 0.02 and δR_eq/R_eq = 0.1 (black, dotted lines). The image of the error bars in terms of fractional size q is shown in the static case (middle panels) and with fast rotation f = 0.2 (right panels). See also Fig. 6.