Must-support in the Smart4Health IG

Must-support flags are used to indicate data elements that systems conforming to a given IG (Implmentation Guide) must support, in an appropriate, IG-specific sense. Such fields are not necessarily required elements, i.e. an instance can be valid even if non-required must-support fields are missing. Indeed, must-support flags has no influence on the validity of a resource, but instead serve to communicate expectations to implementers.

Within the Smart4Health implementation guide, the following semantic for must support is used; If a data element has a must-support flag,it means that

• systems creating resource instances SHALL include the element if its value is known to them, but may leave it out otherwise (required if known)
• systems storing resource instances for further distribution SHALL be capable of storing and processing the element, and of including it in the resource when retrieved
• systems retrieving resources and displaying their content SHOULD be capable of displaying the elements for human use