Hardness-ratio diagrams for XMM-Newton detections of various source classes. Red lines show HR-selection cuts as used for our source classification. a) Detections with optical counterparts in the Tycho-2 catalogue. Galactic stars are shown in black and magenta, SMC-stars in green. Details are given in Sect. 6.1. b) Detections of known pulsars (black) and identified HMXBs (green). See Sect. 6.3. c) Detections of spectroscopically confirmed AGN (black), radio background sources (magenta) and galaxies (green). See Sect. 6.4. d) Detections of sources, screened due to their extent. SNRs are shown in black, other sources (likely galaxy clusters) in green. See Sect. 6.6. e) Comparison of detected SSSs in the SMC and LMC (black) with identified (blue) and classified (cyan) stars in the HR₁-HR₂-plane. See Sect. 6.2. f) Comparison of AGN and radio sources from c) (black) with pulsars and HMXBs from b) (green) in the HR₃-HR₄-plane. See Sect. 6.3.