Left panel: pEW of the Hα absorption profile versus the pEW of the He I λ5876 line measured across the full-time interval (0–40 days). The markers are established by SN type: SNe IIb are shown as blue triangles, SNe II as red circles, and SNe 87A-like as green squares. The colour bars on the right side indicate the SN phase. Right panel: Same as the left panel, but for the FWHM measurements.