Best-fitting results (solid red line in top panel) and the corresponding residuals (bottom panel) for the emission lines (blue dots plus error bars) of SDSS J1251+0613 with a rest wavelength from 6250 Å to 6670 Å. In the top panel, the dashed line in dark green shows the determined power law AGN continuum emissions, the solid green and solid purple lines show the determined broad and probable narrow components in Hα, and the dotted purple lines show the determined components in the [N II] doublet. The vertical dashed lines in dark green mark the positions of the commonly apparent and strong narrow emission lines in blue quasars. In the bottom panel, the horizontal solid red lines show residuals = ±1.