Time evolution of the Doppler velocity at maximum absorption (−v_abs) for Features 1–10 and color-coded by SE SN subtype. Shaded regions correspond to the standard deviation of the rolling mean computed using a window size of ten days and color-coded by spectroscopic subtype as indicated. The rolling windows are evaluated on epochs having a minimum of three measurements and at least two measurements before and after. We note that the peculiar SNe Ic 2009bb and 2009ca are excluded.