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The official version of the OHIE workflows can be found in the OpenHIE Architecture Specification.


Description: This transaction allows a PoS, or any OHIE component, to access terminological information in the terminology service to query for Code Systems.  A typical example would be to request the set of Code Systems defined by HL7.

Both external systems and systems inside the HIE may perform this transaction directly with the TS.  The sequence diagram below shows the steps that occur for a system using this transaction.   

  1. Query Code Systems: What Code Systems have a publisher name that contains 'HL7'?

Sponsor:  Jack Bowie

Status:  This operation has been extensively tested in FHIR Connectathons. 

Referenced Standards and APIs

  • The FHIR Code Systems and supported search parameters are defined in: Searching in FHIR is described in HL7 FHIR Specifications v3.0 or higher support Code Systems. The response is a Bundle of CodeSystem Resources satisfying the search parameters.
  • This workflow implements the IHE IT Infrastructure Technical Framework Supplement - Sharing Valuesets, Codes, and Maps (SVCM) Transaction: Query Code System ITI-Y2.
  • To verify code membership (existence) in a Code System, see the Verify Code Existence workflow.
  • To return detailed information on codes in CodeSystems, see the Lookup Code workflow.

Assumptions and Prerequisites

  • The required Code Systems have been preloaded into the Terminology Service.


  • PoS - The point-of-service system  or other HIE component that is querying for Code Systems.  
  • TS - Stores the curated official version of the Code Systems for the health system.  

Technical details

RefInteractionEndpointDataTransaction Specification
1Query Code System requestTS

The Code System search request is triggered by a PoS or other HIE component.

Input: A set of FHIR search parameters.

FHIR CodeSystem Resource
2.Query Code System responsePoSThe response is sent back to the requesting system. Output: a Bundle of Code System Resources that satisfy the search parameters. FHIR CodeSystem Resource