Now that the researchstudy extension is defined (https://gforge.hl7.org/gf/project/fhir/tracker/?action=TrackerItemEdit&tracker_item_id=15921), can we leverage / incorporate it as a search parameter for a resource (e.g. Observation)?

After implementation as a standard search parameter, the following query would be considered valid:

• http://fhir-server.test/api/observations?researchstudy=XX-YYYY&_count=50 *