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/9374b3b2-0331-4262-a17e-227b06a8f8f3-3435 defines codes, but no codes are represented here