DICOM PS3.18 2021e - Web Services
10.4.3.3.2 Metadata Resource Payload

The payload for a Metadata Resource shall (see Section 10.4.1.1.2) contain all Attributes in the resource. For Data Elements having a Value Representation (VR) of DS, FL, FD, IS, LT, OB, OD, OF, OL, OV, OW, SL, SS, ST, SV, UC, UL, UN, US, UT and UV, the origin server is permitted to replace the Value Field of the Data Element with a Bulkdata URI. The user agent can use the Bulkdata URI to retrieve the Bulkdata.

DICOM PS3.18 2021e - Web Services