a source in a known *star* catalogue in SIMBAD or NED. We also added objects in other catalogues (like 2MASS) which were inspected visually and found to be star-like. We also systematically inspected the counterparts with a match in USNO A2.0 with a magnitude brighter than $R<14$ (usually all the unnamed objects, i.e. not otherwise in SIMBAD or NED, are stars and the rest are galaxies).

Of the 14168 primary counterparts in XXL-N we find 163 ‘spectroscopic’ stars, and visually identify 177 more; 23 were flagged as stars by both methods. In XXL-S, the corresponding numbers are 384, 174, and 7. We note that this screening is not at all complete.

![Distance between the primary counterparts and the X-ray source for sources in XXL-N (in black) and in XXL-S (in red). []{data-label="FigDist"}](astrodist.ps){width="8.2cm"}

Statistics\[SecMWStat\]
-----------------------

Table \[TabMWstat\] lists the number of counterparts sorted by rank. For 60% of the cases (rank$<1$) there is a single counterpart or a counterpart that is clearly preferred. In the remainder of the cases there is some ambiguity in the identity of the real counterpart.

The number of X-ray sources that have no apparent catalogued counterpart at all (‘blank fields’) is very small: 18 in XXL-N 