This change requests seeks to change the Terminologies — Code Systems page of the FHIR specification to align with votes, decisions and policies from the HTA, TSMG and the TSC to establish HL7 Terminology (THO) as the source of truth for external terminologies and their use in HL7 standards. These may be found at the following links:

• THO as the single source of truth for external terminologies
  • HTA: https://confluence.hl7.org/display/TA/Teleconference+2020-09-30
  • TSC: https://confluence.hl7.org/pages/viewpage.action?pageId=91997906 
• Policy: Validating and Requesting Identifiers for an External Code Systems and Identifier Systems
  • https://confluence.hl7.org/display/TA/Validating+and+Requesting+Identifiers+for+an+External+Code+Systems+and+Identifier+Systems 

The following numbered points summarise the changes required to the Terminologies — Code System page in fulfilment of making THO the source of truth for external terminology information:

1. In the preamble of this page the statement: "If a URI is defined here, it SHALL be used in preference to any other identifying mechanisms" should be changed to "For URIs specified here for code systems defined as part of FHIR, they SHALL be used in preference to any other identifying mechanisms."
2. The following statement should be removed, as the list of known identifier systems has been migrated to THO
   • See also the list of known identifier systems that can be used in the system element of the Identifier data type. Additional identifier systems may be registered on the HL7 FHIR registry at http://hl7.org/fhir/registry .
3. In the Important Notes section
   • The following bullet points should be removed as their content refers to external terminologies and thus authoritatively belongs in THO:
     • Note that some of the URNs in this list follow the URN specification in RFC 5141  for referring to standards published by ISO, such as urn:iso:std:iso:11073:10101. Where ISO standards define codes with meanings, and there is no entry in the list above, and they are not registered in the HL7 OID registry, the default URN for the code system is that defined by the RFC 5141.
     • For several of the code systems in this list, multiple systems are given. This means that the variants identified are different code systems, not just variants of the same code system
   • The following bullet points should be added:
     • The external terminology content provided in the Defined Externally tab is provided for convenience and should not be considered authoritative nor normative.
     • Please access the External Code Systems page of HL7 Terminology for authoritative information regarding the correct use of external terminologies with FHIR and other HL7 standards including HL7 endorsed system URI and OID identifiers.
   • The statement "Note that the code systems are available as FHIR resources - see the Downloads Page (as part of the FHIR definitions) (excluding the External code systems." should be reworded as "Note that the HL7 code systems are available as FHIR resources - see the [Downloads Page|downloads.html] (as part of the FHIR definitions)."
4. On the Defined Externally tab itself
   • All rows which do not include a link to a Using X With FHIR (e.g. Using SNOMED CT with FHIR) should be deleted as this information will be available from THO.