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 verify that a code exists in a Code System. 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.
Sponsor: Jack Bowie
Status: This operation has been extensively tested in FHIR Connectathons.
title Verify Code Existence participant PoS participant TS PoS->TS:  Code verification request TS->PoS:  Code verification response
Below enter each interaction that makes up the described workflow above.
|1||Code verification request||TS|
The validate-code request is triggered by a PoS or other HIE component.
Input: A Concept Code and target Code System.
|FHIR CodeSystem Resource, $validate-code operation|
|2.||Code verification response||PoS||The response is sent back to the requesting system. Output: a True or False response.||FHIR CodeSystem Resource, $validate-code operation|