# Reference Set Types

This section describes four categories of reference set types, each of which contain several sub-types.

* [Content Reference Sets](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5%20reference-set-release-files-specification/5.2%20reference-set-types/5.2.1%20content-reference-sets)
  * [Simple Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.1-simple-reference-set.md)
  * [Attribute Value Reference Set](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5-reference-set-release-files-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.3-attribute-value-reference-set)
    * [Component Inactivation Reference Sets](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.3-attribute-value-reference-set/5.2.1.3-attribute-value-reference-set.md)
  * [Association Reference Set](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5-reference-set-release-files-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.4-association-reference-set)
    * [Historical Association Reference Sets](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.4-association-reference-set/5.2.5.1-historical-association-reference-sets.md)
  * [DEPRECATED: Annotation Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.6-deprecated-annotation-reference-set.md)
  * [Query Specification Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.7-query-specification-reference-set.md)
  * [DEPRECATED: Ordered Reference Set](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5-reference-set-release-files-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.8-ordered-reference-set)
    * [Ordered Component Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.8-ordered-reference-set/5.2.1.5-ordered-association-reference-set-1.md)
    * [Ordered Association Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.8-ordered-reference-set/5.2.1.5-ordered-association-reference-set.md)
  * [OWL Expression Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.9-owl-expression-reference-set.md)
  * [Postcoordinated Expression Type Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.1-content-reference-sets/5.2.1.10-postcoordinated-expression-type-reference-set.md)
* [Language Reference Sets](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.2.1-language-reference-set.md)
  * [Language Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.2.1-language-reference-set.md)
* [Map Reference Sets](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5%20reference-set-release-files-specification/5.2%20reference-set-types/5.2.3%20map-reference-sets)
  * [Simple Map from SNOMED CT Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.1-simple-map-from-snomed-ct-reference-set.md)
  * [Simple Map to SNOMED CT Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.2-simple-map-to-snomed-ct-reference-set.md)
  * [Complex and Extended Map from SNOMED CT Reference Sets](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.3-complex-and-extended-map-from-snomed-ct-reference-sets.md)
  * [Map to SNOMED CT with Correlation and Origin Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.4-map-to-snomed-ct-with-correlation-and-origin-reference-set.md)
  * [Code to Expression Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.5-code-to-expression-reference-set.md)
  * [Simple map with correlation from SNOMED CT type reference set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.6-simple-map-with-correlation-from-snomed-ct-type-reference-set.md)
  * [Simple map with correlation to SNOMED CT type reference set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.7-simple-map-with-correlation-to-snomed-ct-type-reference-set.md)
  * [Simple map with correlation from SNOMED CT to SNOMED CT type reference set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.3-map-reference-sets/5.2.3.8-simple-map-with-correlation-from-snomed-ct-to-snomed-ct-type-reference-set.md)
* [Metadata Reference Sets](https://github.com/SNOMED-Documents/snomed-release-file-specification/blob/main/5%20reference-set-release-files-specification/5.2%20reference-set-types/5.2.4%20metadata-reference-sets)
  * [Reference Set Descriptor](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.1-reference-set-descriptor.md)
  * [Module Dependency Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.2-module-dependency-reference-set.md)
  * [Description Format Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.3-description-format-reference-set.md)
  * [MRCM Domain Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.4-mrcm-domain-reference-set.md)
  * [MRCM Attribute Domain Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.5-mrcm-attribute-domain-reference-set.md)
  * [MRCM Attribute Range Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.6-mrcm-attribute-range-reference-set.md)
  * [MRCM Module Scope Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.7-mrcm-module-scope-reference-set.md)
  * [Component Annotation String Value Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.8-component-annotation-string-value-reference-set.md)
  * [Member Annotation String Value Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.9-member-annotation-string-value-reference-set.md)

Each reference set type follows a pattern and that pattern is also represented in a machine readable form using a set of [Reference Set Descriptor ](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.1-reference-set-descriptor.md)members (known as a Descriptor Template, for short). In most case, the same pattern may be used to define a number of different reference sets to serve a variety of purposes. However, there are also some highly specific reference set types that exist for a single specified purpose. These are the [Reference Set Descriptor Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.1-reference-set-descriptor.md), [Module Dependency Reference Set ](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.2-module-dependency-reference-set.md)and [Description Format Reference Set](/snomed-ct-specifications/snomed-ct-release-file-specification/reference-set-release-file-specification/5.2-reference-set-types/5.2.4-metadata-reference-sets/5.2.4.3-description-format-reference-set.md).

In each subsection, a reference set type is described under the following subheadings:

* The purpose of the reference set;
* The format of the reference set member record is detailed in a table;
* The metadata supporting the reference set;
* The machine readable reference set descriptor member records for the reference set type;
* Examples of the reference set type;

Related Links

* [Unicode UTF-8 encoding](/snomed-ct-specifications/snomed-ct-release-file-specification/appendices/appendix-c-unicode-utf-8-encoding.md)

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