Examples of radio components that were joined into one source in the source catalogue. The background images are the DECam z-band cut-outs, the red contours are the 2.1 GHz contours, and the white/blue circles are the flux-weighted positions of the components with a radius of 2.5″. Panels 1–4 show examples of cases 1–4 as described in Sect. 3.7. These examples make it clear that the raw flux-weighted positions are not exactly coincident with the obvious z-band counterparts. This demonstrates the need to manually adjust the position of these kinds of radio sources (see Sect. 3.6). The position adjustments are published in another paper of this series (XXL Paper XXXI).