Definition of the main spectroscopic indicators used in this paper, here illustrated using the Si iiλ6355 line profile in the spectrum of SN 2005ki at t =  +1 d. The right panel shows the pseudo-continuum (dashed line), as well as the wavelength locations of the blue and red emission peaks (λ_blue and λ_peak) and their respective heights (h_blue and h_peak). The wavelength of maximum absorption (λ_abs) serves to define the absorption velocity, v_abs. The peak velocity v_peak is defined analogously. The left panel shows the same line profile normalized to the pseudo-continuum, and serves to define the (relative) absorption depth (d_abs), FWHM, and pseudo-equivalent width (pEW; shaded gray region). In both panels, the thick line corresponds to the smoothed flux, where we have used the inverse-variance weighted Gaussian filter of Blondin et al. (2006) with a smoothing factor dλ/λ = 0.005.