This is the CodeSystem that contains codes in both WHO ATC (http://www.whocc.no/atc) and WHO ATC (http://www.whocc.no/atc).
This code system http://hl7.org/fhir/comparison/CodeSystem/c51c7c25-f5f4-429e-b1c8-849e59890f2d-3429 defines codes, but no codes are represented here