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