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Reference Set Tools allow implementers to create and maintain subsets of SNOMED CT codes for a specific use case.

SNOMED CT subsets Subsets are an important resource in many implementations, grouping concepts in SNOMED CT that apply to a specific use case, like clinical specialties data entry, translations prioritization, data analysis, or others. The tools described in this section allow the implementers to create and maintain SNOMED CT subsets.

Subsets vs Reference Sets vs ValueSets

A subset of SNOMED CT concepts is a defined set of concepts taken from a wider set of concepts, in general from the complete terminology. 

Subsets in SNOMED CT are represented as Simple Type Reference Sets (Refsets), according to the RF2 specifications. The specifications support additional reference set patterns, that allow the users to represent more complex data structures, including additional columns beyond the simple membership to the set.

In HL7 FHIR specifications, subsets are presented as ValueSets. A ValueSet resource instance specifies a set of codes drawn from one or more code systems, intended for use in a particular context. 

. They allow sets of SNOMED components to be grouped together, to support specific use cases, e.g. for data entry of diagnoses for a clinical specialty, for prioritisation of translations, and for data analytics queries. For example, in HL7 FHIR specifications, SNOMED CT value sets are specified in the terminology binding of relevant coded data elements.

Please note that:

• A SNOMED CT subset is a set of SNOMED CT components from a particular SNOMED CT edition.
• A SNOMED CT reference set is a standard format for maintaining and distributing a set of references to SNOMED CT components.
• A SNOMED CT value set is a set of valid concepts or expressions intended to constrain the permissible content for a particular use (e.g. data entry into a particular field).

An implementation requirement for SNOMED CT In the context of a SNOMED CT Implementation, the requirement to create subsets can be satisfied by tools that create any of these components, generic subsets with custom formatshelp users to create generic SNOMED CT subsets, standard RF2 reference sets, or HL7 FHRI ValueSetsvalue sets. The choice of tooling depends will depend on the requirements of other components of the implementation project, especially the terminology server that will be used to provide access to the subsets. 

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implementation artefacts required. For example, a SNOMED CT terminology server may require a SNOMED CT RF2 reference set format.

SNOMED International Reference Set Tool

SNOMED

This tool is maintained by SNOMED International and is used to maintain Reference Sets and Translations for many national extensions.

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• Creation of Extensional and Intensional Simple Type Reference Sets
• Adding members by direct selection, by uploading flat files, or by specifying queries
• Maintenance tasks related to the update to new releases of dependencies
• Collaborative workflow for content revisions
• Refset export for publication
• Management of refset metadata
• Refset directory

Other Subset Tools

Other SNOMED CT subset tools are available, as listed below.

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Please note that this list of subset tools is provided in alphabetical order. To request the addition or removal of a subset tool to/from this list, please submit a request via the 'Feedback' button at the bottom of this page.