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 AMT Medicinal Product and Substances (http://terminology.hl7.org.au/ValueSet/amt-mp-codes). E.g. what you have to deal with if you get resources containing codes in either of them