This is the ValueSet that contains all the codes in Research Study Classifiers (http://hl7.org/fhir/ValueSet/research-study-classifiers) and ICH M11 Amendment Details Statement Value Set (http://hl7.org/fhir/uv/ebm/ValueSet/ich-m11-amendment-details-statement). E.g. what you have to deal with if you get resources containing codes in either of them