Dips formed by the coupling between (k = 0, m = −1) gravito-inertial modes in the envelope and (l = 3, m = −1) pure inertial modes in the core, in the co-rotating frame related to the envelope. Different panels correspond to coupling parameters of respectively ϵ = 6.19 × 10⁻³, 1.24 × 10⁻², 7.43 × 10⁻², which give Γ = 1.0 (top), 4.0 (middle), and 12.0 h (bottom) in the case of no differential rotation. For each panel, period-spacing patterns are superimposed on one another, taking values of α_rot = Ω_env/Ω_core in [0.80, 0.90, 0.95, 0.98, 1, 1.02, 1.05]. The period-spacing series in red shows the case of no differential rotation.