Evolution of absorption minima for SN 2015H for a selection of lines that show minimal blending. For comparison, we show velocities measured for Fe ii λ6149 for both SN 2002cx and SN 2005hk. Given in black is a typical error bar for measured velocities. Points marked with grey crosses indicate velocities of Fe ii λ6247 measured for the N3def model (see Sect. 5), at the three epochs shown in Fig. 12. Measurements of velocity will be affected, to some degree, by Monte Carlo noise present in the model. We, therefore, estimate a median velocity of these three epochs ±2 d, with the uncertainty given by the standard deviation of these measurements.