> For the complete documentation index, see [llms.txt](https://guides.ohie.org/arch-spec/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guides.ohie.org/arch-spec/dev-1/introduction/terminology-service-workflow/verify-code-existence.md).

# Verify Code Existence

This transaction allows a PoS, or any OHIE component, to access terminological information in the terminology service to verify that a code exists. A typical example would be to validate that the codes contained in an incoming patient data message are, in fact, from a required code system, e.g. ICD-10 or LOINC.

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. Existence: Is a Concept Code present in a specified Code System. E,g., is '123XYZ' a valid Code in the ICD-10 Code System?

| Workflow Maturity             | <p><img src="https://lh5.googleusercontent.com/Vp6XBRGu-U_Dmd5EKNpCZvEEum0CxOcHOj9NgHh8UMMNLMlXHmLcUE_YWueDRr4uqWLzpPfzSBLJ2k33XQIelLypjQ4wyrD17-t33GtLa8fFxW9AYDvXhiJmBl4VaLgKDg" alt=""></p><p> <strong>Mature</strong></p> | <ul><li><strong>One or more OpenHIE implementations of this workflow exist in one or more countries</strong></li><li><strong>Workflow is defined and ARB approved</strong></li><li><strong>Workflow is supported by mature standards</strong></li></ul>                                                                                                                                                                                                                                                                                                        |
| ----------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Standards\*                   |                                                                                                                                                                                                                               | <p>The FHIR CodeSystem validate-code operation: <a href="http://build.fhir.org/codesystem-operation-validate-code.html"><http://build.fhir.org/codesystem-operation-validate-code.html></a>. HL7 FHIR Specifications v3.0 or higher support validate-code. The response is a Boolean (true or false) based on whether the code exists in the specified CodeSystem.</p><p>This workflow implements the IHE IT Infrastructure Technical Framework Supplement - Sharing Valuesets, Codes, and Maps (SVCM) Transaction: Validate Code ITI-Y5 for Code Systems.</p> |
| Assumptions and Prerequisites |                                                                                                                                                                                                                               | The required CodeSystems have been preloaded into the Terminology Service.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Actors                        |                                                                                                                                                                                                                               | <ul><li>PoS - The point-of-service system or other HIE component that is requesting to verify a code.</li><li>TS - Stores the curated official version of the terminology and codes for the health system.</li></ul>                                                                                                                                                                                                                                                                                                                                           |

## Interaction Description

The following is a description of the interaction steps.

![](https://lh5.googleusercontent.com/tVcE12rhH8Qu9ouNomMiBBhudn6nPwbbxMhMMD4Xd3cLTErV3U-mF0d63-2tX9CDXJX3NMn9R7z1nzIOYg3rhtg0_yFgAv0bwI5YrO-YYqnbv5JmIVN7fcls68f5ULMQNw)

| Ref | Interaction                | Data                                                                                                                               | Transaction Options                                |
| --- | -------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------- |
| 1   | Code verification request  | <p>The validate-code request is triggered by a PoS or other HIE component.</p><p>Input: A Concept Code and target Code System.</p> | FHIR CodeSystem Resource, $validate-code operation |
| 2   | Code verification response | The response is sent back to the requesting system. Output: a True or False response.                                              | FHIR CodeSystem Resource, $validate-code operation |