This is the ValueSet that contains all the codes in eHDSI Absent Or Unknown Problem (http://terminology.ehdsi.eu/ValueSet/eHDSIAbsentOrUnknownProblem) and eHDSI Absent Or Unknown Problem (http://terminology.ehdsi.eu/ValueSet/eHDSIAbsentOrUnknownProblem). E.g. what you have to deal with if you get resources containing codes in either of them