http://hl7.org/fhir/StructureDefinition/artifact-url|5.2.0

An absolute URI that is used to identify this artifact when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which an authoritative instance of this artifact is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the artifact is stored on different servers.