General Guidance

Extensibility – “additional” elements

A server may send “additional” elements beyond those flagged with Must Support in an CA Core+ profile. Additional elements are often required by other profiles the system may conform to, allowing local requirements, including technical and workflow context for the resource, to be reflected and extending the health information supported in exchanges. For this reason, extensibility is generally encouraged and expected in CA Core+ profiles. Only in some exceptionally rare use case profiles are rules tightened to limit the nature of additional information that can be sent. Specification authors should strive to enable greater interoperability and software re-use by not reducing an element’s cardinality.

Depending on local requirements, a client application may ignore these “additional” elements, may treat the data as for rendering only, or be capable of recognising and using the element.