\sigma$ radio contours (21 sources);

2.  possible match – looks likely but there are other sources within the $3 \sigma$ radio contours (23 sources);

3.  confused – several sources within the $3 \sigma$ radio contours so cannot identify the correct match (8 sources);

4.  no match – no sources within the $3 \sigma$ radio contours (5 sources).

Examples of sources assigned each of these flags are given in Fig. \[fig:ext-matching\]. Table \[tab:optical-matches\] contains a summary of the number of matches to the Data Fusion catalogue and the flags used in the catalogue.

![Separation between the best radio position for each source and the position of its counterpart in the Data Fusion catalogue. Sources which are considered extended for the purposes of matching are shown by ‘$+$’ (blue in the online version), compact sources are shown by ‘$\times$’ (red in the online version). The circle indicates a separation of 2 arcsec (the match radius for compact sources).[]{data-label="fig:best_fused_sepn"}](FUSED_best_diff-eps-converted-to.pdf){width="\columnwidth"}

  Description                                   No. of sources
  ------------------------------------------- ----------------
  Extended – probable match                                 21
  Extended – possible match                                 23
  Extended – confused                                        8
  Extended – no match                                        5
  Compact – match within 2 arcsec                           36
  Compact – no match within 2 arcsec                         2
  10C position only – 