<ResearchSubject xmlns="http://hl7.org/fhir"><id value="example-crossover-placebo-to-drug"/><identifier><value value="ecsr45"/></identifier><status value="active"/><period><start value="2022-06-10"/></period><study><reference value="example-ctgov-study-record"/></study><subject><reference value="cfsb1676546565857"/></subject><comparisonGroup><concept><coding><system value="http://hl7.org/fhir/example-comparison-group"/><code value="placebo"/><display value="Placebo"/></coding></concept></comparisonGroup><comparisonGroup><concept><text value="ap303"/></concept></comparisonGroup></ResearchSubject>