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The Welsh Reference Data and Terminology Service (WRTS)


The Welsh Reference Data and Terminology Service (WRTS) maintains reference data on behalf of NHS Wales. The content itself is maintained by the team whom reside in the Digital Strategy Directorate of the Digital Health and Care Wales (DHCW).


The service maintains and distribute Systematised Nomenclature of Medicine -- Clinical Terms (SNOMED CT) and supplies FHIR compliant (where applicable) code systems, value sets and concept maps to clinical systems across NHS Wales in a secure, resilient and consistent manner.


It provides a central repository for reference data, which is available in different forms and ensures reference data is available on demand, via a variety of means.  This reference data is used for a variety of purposes including validation, derivation of new values, the supply of nationally recognised codes in clinical IT systems and the labelling of outputs for reporting purposes.  This reference data is used for both Primary (i.e. direct patient care) and Secondary use purposes.


The Reference Data Team in DHCW support the maintenance of Welsh national codes used throughout the United Kingdom in NHS systems.


The Team is responsible for:

  • Maintaining and distributing Systematised Nomenclature of Medicine -- Clinical Terms (SNOMED CT) code

  • Maintaining all Wales organisation site codes; 

  • Providing a central repository for national codes; 

  • Providing the reference data to support the NHS Wales Data Switching Service and National databases; 

  • Maintaining the SNOMED CT Codes & reference data for Welsh national systems used in the Health Boards; 

  • Maintaining Welsh Code systems and value sets

  • The development of national standards along site the national Data Standards Team relating to new types of reference data; 

  • Providing a helpline to answer all queries, request for changes

  • Providing guidance on the use of SNOMED CT and reference data.


When clinical information is shared between organisations and computer systems uses codes to ensure treatments, organisations and hospital locations are always described in the same way. We provide support for the data sets used by the different coding structures through our reference data service.


For all queries, please contact the Welsh Reference & Terminology Service using the contact details below:




Reference Data:

Service Point:


Digital Health and Care Wales

Tŷ Glan-yr-Afon 

21 Cowbridge Road East 


CF11 9AD