Average 20 GeV–300 TeV flux as a function of the average 0.2–12 keV flux for the 77 TeVCAT sources in our sample. The data points are color-coded according to class, using the same coding as that described in Figure 2. In the plot, we also include the best-fit linear regression between the logarithm of the VHE flux and the logarithm of the X-ray flux, i.e., for the whole sample (dashed black line) and for the BZB subsample (violet dashed line). For reference, we also plot the 1:1 relation (solid black line).