Distribution of M_LC (top left), M_BH (top right), q (bottom left), and P (bottom right) in DR3 and DR4. In the legend, ‘Underlying’ is the distribution of all simulated OB+BH systems, ‘Detected’ are those systems detected as binaries by Gaia, and ‘Identified’ are Class III systems (i.e. confirmed OB+BH systems). The last systems are the observational distributions that can be expected to be constructed using the OB+BH systems identified in the respective data release.