DV_DURATION Duration to DV_DURATION Problem openEHR uses the ISO duration meanwhile, FHIR uses UCUM codes. Therefore, the mapping needs to transform FHIRs representation using UCUM codes to iso8601 Mapping CommonUCUMCodesForDuration into the iso standard of P[nnY][nnM][nnW][nnD][T[nnH][nnM][nnS]]. The UCUM codes are stored in code of the Duration, along with the value. Unit ISO 8601 Format Description ms T[00H]00M[00S] Milliseconds (can be represented as fraction of a second) s T00H00M00S Seconds min T00H00M Minutes h T00H Hours d P00DT00H00M00S Days wk P00Y00M00W Weeks mo P00Y00M Months a P00Y Years FHIRpath Cardinality (FHIR) Comment openEHR Cardinality (openEHR) Comment value 0..1 combined with code, see description above value 1..1 comparator 0..1 - unit 0..1 - code 0..1 - system 0..1 - DV_DATE_TIME DV_MULTIMEDIA