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/d90c6776-070a-4707-b535-0a35f2e2298a-3435 defines codes, but no codes are represented here