is only nominally better than the secondaries, but it is indicative of an intrinsic ambiguity.

Finally, we tie everything together by comparing the ranks assigned by the different methods, cleaning up ambiguous counterpart sets sharing a counterpart in more than one survey, demoting to secondaries the detection in just the surveys with poorer position resolution (WISE, IRAC, GALEX) and promoting the cases with counterparts in several surveys.

We assign a final rank (numbers provided in Table \[TabMWstat\]) so that each X-ray source has a single *primary counterpart*, and zero, one, or more *secondaries*. Rejected counterparts will not be listed in the multiwavelength catalogues. The identification rank is coded by a three-character string. There will be always *one primary* counterpart with rank between 0 and 1, and there may be one or more *secondary* counterparts with rank above 2. The codes are as follows:

-   **0.0** physically single counterpart within 10  of the X-ray position;

-   **0.1** logically single counterpart (all others were rejected);

-   **0.2** ‘recovered’ (the single counterpart has bad estimators);

-   **0.4** ‘blank field’ (no catalogued counterpart within 10  of the X-ray position;

-   **0.9** the primary counterpart is much better than all the secondaries (ranked 2.2);

-   