Glossary · Terminology

VSAC

Value Set Authority Center

Updated 29 October 2026

VSAC is the NLM repository of US value sets, where authors such as CMS and HL7 publish the code lists used in quality measures, C-CDA and FHIR guides.

It offers a FHIR terminology API and needs a free UMLS licence, so implementers can expand official value sets instead of copying codes by hand.

Official source

NLM Value Set Authority Center

VSAC

Official source

See also

Explained in depth

FHIR terminology servers explained: $lookup, $validate-code, $expand, $translate and $subsumes, with requests