DICOM PS3.18 2019a - Web Services
6.10.3.4.2 Behavior

The origin server shall perform the search indicated by the request, using the matching behavior specified in Section 6.7.1.2 and in the corresponding sections in Table 6.10.3.4.1.2.1-1, and return a response containing the search results, or an appropriate Status Report.

The rules for search results are specified in Section 6.7.1.2.

DICOM PS3.18 2019a - Web Services