Spectra of SN 2023ixf at 199 d and 249 d compared with those of Type IIP SN 2017eaw at 205 d and Type Ic SN 2020oi at 63 d. All spectra are shifted back to z = 0, and the spectra of SN 2017eaw and SN 2020oi are multiplied with constants for visual comparison. Rest wavelengths of the CO first overtone emission band heads for 2–0, 3–1, 4–2, 5–3, 6–4, 7–5, and 8–6 transitions are 2.294, 2.323, 2.353, 2.383, 2.414, 2.446, and 2.479 μm, respectively (marked as thick black lines).