Cross-calibration of the S/N (flux divided by computed flux error) vs. the detection statistic PNT_DET_STAT for the soft (left) and hard (right) X-ray bands. The red and green dots correspond, respectively, to point-like sources in XXL-N and XXL-S. The solid thick line is a linear fit in log–log space to the S/N averaged in pseudo-logarithmic (the pseudo-logarithmic binning is a spacing of 1 in PNT_DET_STAT up to 100, then 5 up to 1000, 50 up to 10 000, and 500 above 10 000) likelihood bins. The two pale grey horizontal lines are fiducial marks for the 3σ and 4σ levels. The equivalent dotted vertical lines are for PNT_DET_STAT of 65 and 115.