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Value Set Definitions and Expansions

All value sets have one or more definition versions, and each definition version for a value set has one or more expansion versions.

Value Set Definitions

Value set definitions include characteristics that an author uses to describe a value set. The extensional value set definition includes the author’s enumeration of terminology codes defined by the value set. The intensional value set definition enables authors to intensionally define value set terminology code content as a logical statement (e.g., all codes that are descendants of this code). Value set definitions exist only in the VSAC Authoring Tool. Value set metadata, which are part of the overall value set and not linked to the value set definition, include the following elements: value set name, value set OID, note, purpose statements, author group, and steward group.

Value Set Expansion

Value set expansions are computed by VSAC algorithms from each value set definition, created by authors in the VSAC Authoring Tool, using an author-designated expansion profile calculation of specified code system versions. The "Most Recent Code System Version in VSAC" expansion profile calculation consists of the most recent code system versions available in VSAC.

Value set expansions are snapshots-in-time of value set definitions computed by VSAC using author-specified expansion profiles or code system versions. Value set expansions exist only in the “Search Value Sets” tab (the public repository). VSAC will calculate value set expansions using the value set definitions chosen by the author or steward.

Last Reviewed: March 12, 2024