> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-international-documents/snomed-ct-glossary/e/extensionally-defined-subset.md).

# extensionally defined subset

## extensionally defined subset

A subset whose membership is defined by an extensional subset definition.

An extensional subset definition is defined as

* A subset in which the members are represented by enumeration.

#### Notes

* An extensional subset definition of SNOMED CT components may be represented by a list of the identifiers of the components.
* The standard format for distributing an extensionally defined subset of SNOMED CT components is a simple reference set.

## Related

* [Extensional and Intensional definitions](https://en.wikipedia.org/wiki/Extensional_and_intensional_definitions)

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