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/21d0d52d-6932-4516-ad29-944d62abcb69-3432 defines codes, but no codes are represented here