A demonstration project to use ResearchStudy for a trial registry has identified some search requirements.

These seem easy to add and improve useability significantly, in the short term.

Trial Phase is not searchable. Seems a key parameter that people would want to search on.
Propose add search param on .phase

Users want to search for trials with certain eligibility critera.
This is expressed in .recruitment.eligibility, and then in a Group.
But there is no search parameter so it doesn't work.
Propose add .recruitment.eligibility as reference search parameter

Users want to search on trial objectives.
Propose add .objective.description (and why not also .objective.type)

Users want to search on observational vs interventional
Propose add studyDesign

Others, that analysts have not yet identified a need to search on in this project, but seem obviously needed -
Propose add:
.name
.description
.focus (so you can search on the name of the drug)
.period
.classifier