Échelle diagrams of the RGB star KIC 9882316, which shows no rotational signature. Left: classical frequency échelle diagram as a function of the dimensionless frequency ν/ Δν−(n_p + ε). The radial order n_p is indicated on the y-axis. Radial modes (in red) are centred on 0; quadrupole modes (in green) near −0.12, with a radial order n_p−1; and ℓ = 3 modes (sometimes observed; in light blue) near 0.22. Dipole mixed modes are identified with the frequency given by the asymptotic relation of mixed modes, in μHz. The fit is based on peaks showing a height greater than eight times the mean background value (grey dashed lines). Middle: classical period échelle diagram, where the abscissa is the period modulo the period spacing ΔΠ₁. The most prominent mixed modes, marked with blue filled squares (in light blue for peaks in the vicinity of p-m modes), are automatically identified. In the background of the figure, the spectra are plotted twice and top to tail to make the mode identification easier, with the pressure radial orders indicated on the radial modes. Right: stretched period échelle diagram, where the abscissa is the stretched period τ modulo the period spacing ΔΠ₁. Pressure-dominated mixed modes are coded in light blue.