# Historical Association Reference Sets ## Purpose Historical Association Reference Sets are used to link concepts that have been inactivated to active concepts that represent an identical, similar or possible meaning of the inactivated concept. Historical Association Reference Sets follow the release file specification documented in [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/5.2.1.4-association-reference-set.md) with the inactive concept represented by the referencedComponentId, the type of association represented by the refsetId and the related active concept represented by the targetComponentId. The following subsections identify the metadata used to represent different types of historical associations. ## Metadata The following metadata supports this reference set: **Historical Association Reference Set names in the metadata hierarchy** > [900000000000455006 |Reference set|](http://snomed.info/id/900000000000455006)\ > [900000000000521006 |Association type|](http://snomed.info/id/900000000000521006)\ > [900000000000522004 |Historical association|](http://snomed.info/id/900000000000522004)\ > [900000000000523009 |POSSIBLY EQUIVALENT TO association reference set|](http://snomed.info/id/900000000000523009)\ > [900000000000524003 |MOVED TO association reference set|](http://snomed.info/id/900000000000524003)\ > [900000000000525002 |MOVED FROM association reference set|](http://snomed.info/id/900000000000525002)\ > [900000000000526001 |REPLACED BY association reference set|](http://snomed.info/id/900000000000526001)\ > [900000000000527005 |SAME AS association reference set|](http://snomed.info/id/900000000000527005)\ > [900000000000528000 |WAS A association reference set|](http://snomed.info/id/900000000000528000)\ > [900000000000529008 |SIMILAR TO association reference set|](http://snomed.info/id/900000000000529008)\ > [900000000000530003 |ALTERNATIVE association reference set|](http://snomed.info/id/900000000000530003)\ > [900000000000531004 |REFERS TO concept association reference set|](http://snomed.info/id/900000000000531004) *** ## Historical Association Rules and Guidance Each member of a [|Historical association Reference Set|](http://snomed.info/id/900000000000522004) represents a reference from an inactive component to other equivalent or related components that were current in the Release Version in which that component was inactivated. Each [|Historical association Reference Set|](http://snomed.info/id/900000000000522004) represents a different type of association between the components referred to by the referencedComponentId and the targetComponentId as shown in the Table below. **Association reference set types in the International Release of SNOMED CT**
Association reference setDescriptions
|POSSIBLY EQUIVALENT TO association reference set|Applies to a concept that is ambiguous. The targetComponent is an active concept that represents one of the possible meanings of the inactive concept . Multiple rows are used to refer to each of the possible meanings of the ambiguous concept.
|MOVED TO association reference set|Applies to a component that has been moved to (or are pending a move to) another namespace. The targetComponent identifies the target namespace (not the new component).
|MOVED FROM association reference set|Applies to a component that has been moved to this namespace from another namespace. The targetComponent identifies the original componentIdentifier in its previous namespace.
|REPLACED BY association reference set|Applies to an erroneous, obsolete and other inactive component for which there is a single active replacement. The targetComponent identifies the active component that replaces this component.
|SAME AS association reference set|Applies to a component that is a duplicate. The targetComponent identifies the active component that this component duplicates.
|WAS A association reference set|Links an inactive classification concept such as "not otherwise specified" or "otherwise specified" with the active concept that was formerly its most proximal supertype.
|SIMILAR TO association reference set|(not used currently)
|ALTERNATIVE association reference set|Links an inactive classification concept derived from ICD-9 Chapter XVI "Symptoms signs and ill-defined conditions" with the most similar active concept.
|REFERS TO concept association reference set|Applies to an inactive description which is inappropriate to the concept it is directly linked to but instead should refer to the concept referenced by the targetComponent.
*** The component identified by the targetComponentId must be an instance of the same class of component as the component identified by the referencedComponentId for all Historical association reference sets apart from the |REFERS TO concept association reference set|. ## Reference Set Descriptor and Example Data {% hint style="info" %} **Notes on the tables used to show descriptors and examples** The reference set example tables on this page have been revised as follows to aid clarity and understanding: * The first four columns which are present in all release files are not shown. The omitted columns (id, effectiveTime, active, moduleId) are used in the same way in all referenced sets to support identification, versioning and packaging. They do not directly affect the specific features of a particular reference set or reference set type. * Reference set columns that contain SNOMED CT identifiers are expanded to show details of the concept or description referenced by that identifier. In some cases, the term is shown in the same column using the expression syntax, in other cases an additional column with a name suffix '\_term' has been added. In the standard reference set files only the identifier is present in the column and there is no added column for the term. When using reference sets, the term and other details of the component are looked up from the relevant component release files. {% endhint %} #### Descriptor Template The tables below show examples of the descriptors for specific reference sets that follow the [|Association type reference set|](http://snomed.info/id/900000000000521006) pattern. **Refset Descriptor rows for the SAME AS association reference set**
refsetIdreferencedComponentId (Referenced component)attributeDescription (Attribute description)attributeType (Attribute type)attributeOrder (Attribute order)
900000000000456007 |Reference set descriptor|900000000000527005 |SAME AS association reference set|900000000000532006 |Association source component|900000000000460005 |Component type|0
900000000000456007 |Reference set descriptor|900000000000527005 |SAME AS association reference set|900000000000532006 |Association source component|900000000000460005 |Component type|1
*** #### Example Data The following table holds example entries for the [|REPLACED BY association reference set|](http://snomed.info/id/900000000000526001). **Sample content from**
refsetIdreferencedComponentId (Association source component)targetComponentId (Association target component)
900000000000526001 |REPLACED BY association reference set|100005 |SNOMED RT Concept|138875005 |SNOMED CT Concept|
900000000000526001 |REPLACED BY association reference set|212002 |Salmonella III arizonae 53:k:z|398450001 |Salmonella IIIb 53:k:z|
900000000000526001 |REPLACED BY association reference set|225005 |Special care of patient with contagious disease|133895001 |Care of patient with infectious disease|
900000000000526001 |REPLACED BY association reference set|244003 |Evans and Lloyd-Thomas syndrome|66659007 |Normal variation in position|
900000000000526001 |REPLACED BY association reference set|278009 |Epidural injection of neurolytic substance, lumbar|17753007 |Epidural injection of neurolytic solution, lumbar|
900000000000526001 |REPLACED BY association reference set|558000 |Other disorder of the neurohypophysis, NEC|72442006 |Disorder of posterior pituitary|
900000000000526001 |REPLACED BY association reference set|659001 |Peptostreptococcus anaerobius|413524006 |Anaerococcus tretradius|
900000000000526001 |REPLACED BY association reference set|696005 |Chronobiologic disorder|387605007 |Abnormal chronobiologic state|
900000000000526001 |REPLACED BY association reference set|700002 |Salmonella III arizonae 50:z4,z23,z32:--|404619004 |Salmonella IIIa 50:z4,z23,z32:-|
900000000000526001 |REPLACED BY association reference set|822000 |Salmonella arizonae 53:z4,z23:--|13998005 |Salmonella IV 53:z4,z23:--|
*** ## Relevant References * Practical Guide to Reference Sets [Representing Historical Associations](/snomed-ct-practical-guides/snomed-ct-reference-set-guide/3-requirements-and-use-cases/3.2-use-cases/3.2.6-maintenance-and-management.md) Provide Feedback --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.snomed.org/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?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.