From Kevin Snow at Envision:

We need to develop a strategy for calling different versions of API version (different FHIR version, contraindication type resources are added in the future) if this happened would we want to create a new FHIR operation name or simply an updated version. If it's an updated version should be have the ability to call by version number and what we do to ensure we maintain backwards compatibility if we move forwards with adding something like risks i.e. - how do we ensure no breaking changes.