> 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/m/mapping-reference-set.md).

# mapping reference set

## mapping reference set

A reference set designed to support the process of mapping data from one code system, classification, or terminology to another code system, classification, or terminology.

#### Notes

* There are several types of *mapping reference set* each of these supports different types of mapping.
  * Simple Map from SNOMED CT Reference Sets and Simple Map to SNOMED CT Reference Sets support one-to-one maps from or to SNOMED CT.
  * Complex and Extended Map from SNOMED CT Reference Sets support maps where additional information is required to determine the correct mapping from SNOMED CT to a statistical classification such as ICD-10.
  * Maps which have a requirement to indicate the degree of correlation between a SNOMED CT concept and other codes. (See Map Reference Sets which use "correlation" within their type / name.)
  * Code to Expression Reference Sets support maps from other code systems in cases where some or all the source codes may need to be represented by a postcoordinated expression.

## Alternatives

* **Cross mapping**

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