Illustration of some profile morphologies in model s15p2Pwr1e40 at 700 d together with the observations of SNe 2017eaw at 900 d and 2017ivv at 520 d. The spectral region shown is centered on the rest wavelength of Hα. At the top, the flux contributions associated with O I (dotted line; primarily associated with [O I] λλ 6300, 6364) and H I (dashed line; primarily associated with Hα) are shown. The residual flux offset in this spectral region is primarily due to a forest of Fe I and Fe II lines.