Polarization degree P (top panel) and angle θ (bottom panel) for SN 2017gmr at five different epochs: 58045.60, 58067.24, 58099.86, 58108.76, and 58 134.93 (MJD; purple, green, sky-blue, orange, and yellow symbols, respectively). The data are binned to 5 Å. The gray lines at the bottom of each plot represent the total-flux spectra on 58 134.93 (MJD). The red lines show the polarization degree and angle of the ISP as approximated by P(λ) = P_maxexp[−Kln²(λ_max/λ)] with fixed values of P_max = 0.35, λ_max = 6400 Å and K = 4.0, and θ_ISP = 33.37. The blue shading shows the wavelength windows at the adopted lines, where at all epochs the flux was > 1.1 times higher than in the nearby continuum regions.