> 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/h/historical-reference-set.md).

# historical reference set

## historical reference set

A reference set that provides information about concepts or descriptions that have been inactivated.

#### Notes

* There are two types of *historical reference sets* :
  * Inactivation Reference Sets which indicate the reason for inactivation of a particular component.
  * Historical Association Reference Sets which associate inactive concepts with one or more active concepts that represent the same, similar or a possible meaning of an inactive concept.

##

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