This is the ValueSet that contains all the codes in Medicine Active Substances - IPS (http://hl7.org/fhir/uv/ips/ValueSet/medicine-active-substances-uv-ips) and Medication Ingredient (https://healthterminologies.gov.au/fhir/ValueSet/medication-ingredient-1). E.g. what you have to deal with if you get resources containing codes in either of them