Emission line fitting procedure examples. Top: Example on the H_α line in spectrum 3. The three panels show, respectively, the best fit model obtained with one, two, or three Gaussians, and their respective residuals. The spectrum is represented by the black markers while the blue lines show the individual Gaussian components. The semitransparent band shows the 3σ uncertainty of the total model. The vertical dashed line indicates the rest-frame centroid of H_α. Bottom: Example on the triple-peaked H_β line in spectrum 5. The vertical dashed line indicates the rest-frame H_β centroid.