Flare-kernel spectra from the region inside the green rectangle in Fig. 12: (left-middle) the spectrogram at the time of the rectangle region in Fig. 12, with before (top) and after (bottom) spectrograms. Right: spectra and their fits (dashed lines) at the positions marked by the green lines in the left panel. The vertical solid lines indicate the rest wavelength of Fe xxi, and the vertical dash-dotted lines indicate the rest wavelength of C i. The green solid line is the background, the blue dashed line is the background + Fe xxi line fit, and the red dashed line is the background + C i line fit.