The q and u spectra of SN 2011fe from Epoch 4 compared to the values chosen for q(ISP) and u(ISP). The solid blue line shows the weighted average of the 4600–5400 Å wavelength range for Epochs 4–10. The dot-dashed red line shows the average from the wider 4000–7000 Å wavelength range for Epochs 4–10. The blue and red shaded regions show the standard deviations of the individual epoch averages compared to the overall average values.