Locations of the resonant equilibrium points in the a_i+1∕a_i vs. planes, i = 1, 2, for three equal-mass planets in a 3:2 – 2:1 mean motion resonance chain, close to which Kepler-305 resides. Orange vertical lines show the exact nominal commensurability, while dashed vertical lines show the observed a₂ ∕a₁ and a₃ ∕a₂ in the case of Kepler-305. As explained in the text, we select one equilibrium configuration (indicated by the red dot in both panels) by requiring that (a₃ ∕a₁)|_eq ≡ (a₃∕a₁)|_obs, which automatically fixes all orbital elements a₂∕a₁, a₃ ∕a₂, e₁, e₂ and e₃ along the equilibrium curves.