"Contains the identifier of the medical substance/treatment administered.... If the substance administered is a vaccine, CVX codes may be used to code this field...." - HL7 Version 2.8, RXA-5 “A role for the product when merely refered to as one that might be administered. This is the role through which the product model would be entered for electronic prescribing.” – HL7 Version 3 (Role->AdministerableMaterial). "Identifies the medication that was administered. This is either a link to a resource representing the details of the medication or a simple attribute carrying a code that identifies the medication from a known list of medications." - HL7 FHIR, MedicationAdministration.medication[x]