QI-Core Implementation Guide, published by http://www.hl7.org/Special/committees/cqi/index.cfm. This is not an authorized publication; it is the continuous build for version 5.0.0). This version is based on the current content of https://github.com/HL7/fhir-qi-core/ and changes regularly. See the Directory of published versions
This page lists the Extensions defined as part of the QI Core Implementation Guide. A registry of standard extensions can be found in the FHIR specification and additional extensions may be registered on the HL7 FHIR registry.