Photon index distribution of the NLS1 DR12 eRASS1 sample as obtained from a simple power-law fit when freezing N_H only if necessary to obtain a valid fit (filled). The mean photon index is 2.81 ± 0.03. About 10% of the sources are located in the super-soft tail with photon indices between 4 and ∼10. The white within the filled histogram is the best-fit value for sources with X-ray counts greater than 50 (mean: 2.99 ± 0.05), and the line is the distribution of the 90% confidence lower bounds with a mean of 1.94 ± 0.02.