Panel a: number of candidates in the ComPRASS catalogue that were either confirmed or not and/or identified with the external validation described in Sect. 3. Confirmed (class 1) refers to the candidates that are associated to an already confirmed cluster; Identified not confirmed (class 2) indicates the candidates that are associated to candidates in X-ray or SZ catalogues that have not yet been confirmed; and New (class 3) represents the candidates that are not associated to any cluster or cluster candidate. Identified includes candidates in class 1 and class 2. The different colours in the three middle bars correspond to the catalogue in which they were confirmed and/or identified: MMF3 (yellow), Planck (green), SPT (red), ACT (orange), MCXC (blue), redMaPPer (violet), Abell (grey), Zwicky (brown), other SDSS-based catalogues (lavender), high-redshift catalogues (dark blue), additional clusters found in NED/SIMBAD (dark green), and Burenin (2017) (pale pink). Since one candidate may have been identified with several catalogues, the indicated colour refers to the first one in the previous list. For example, red indicates the candidates identified/confirmed by SPT and not identified/confirmed by Planck. Panel b: number of candidates in the ComPRASS catalogue that were identified with the different catalogues. This includes both class 1 and class 2 candidates. For the Planck catalogues, the candidates identified with MMF3 are indicated in yellow, while the others are shown in green. For the MCXC catalogue, RASS and serendipitous clusters are indicated in medium and light blue, respectively.