Constraints of M = 2.14 ﹩{M}_{\odot }﹩ (green surface), R_1.4 = 12.83 km (yellow surface), Λ_1.4 = 580 (red surface), R_1.28 = 11.52 km (orange surface), and the causality condition (blue surface) in the 3D parameter space of K_sym–J_sym–J₀. The black arrows show the directions supporting the corresponding constraints and the red arrows direct to the corresponding surfaces. Modified from Figure 4 of Zhang & Li (2020).