Use of extensions
“Note that, unlike in many other specifications, there can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core simplicity for everyone.”
The FHIR standard has a strict way to define extensions in resources.This is the only way to define extensions. An implementer SHALL take extra note of the rules concerning modifier extension.
When going beyond the profiles in this guide, a project SHALL at least try to express its data using the bare FHIR standard and adapt its business rules accordingly.
When an extension is needed and there is already an extension: this existing extension SHALL be used. In general, Belgian profiling on resources will endeavour to – when needed – only use the extensions already defined by HL7. In the Belgian profiling documentation, some available standard HL7 extensions of certain resources are recommended.