The single trial significance obtained from the Gaussian line scan with different line widths (500, 1500, 4500 km/s) over the rest-frame spectra of 1H 1934-063 in the RGS band. The vertical dashed blue lines represent the rest-frame energies of the known ion transitions as a reference, while the red lines and the shaded region respectively correspond to the centroid and 1σ uncertainties of the prominent UFO absorption lines detected in the following photoionization modeling. The gray region marks the 3σ significance.