This is the ValueSet that contains all the codes in Problem Category Value Set (https://www.ehealth.fgov.be/standards/fhir/core-clinical/ValueSet/ProblemCategoryVS) and Problem Category Value Set (https://www.ehealth.fgov.be/standards/fhir/core-clinical/ValueSet/ProblemCategoryVS). E.g. what you have to deal with if you get resources containing codes in either of them