Appendix B: Editions, Versions and Extensions
This appendix explains the different types of SNOMED CT editions, versions, and extensions. It also outlines the requirements for terminology services and applications that use them.
Requirements
Terminology service providers must deliver services that can load data from SNOMED CT release packages that conform to the Release File Specifications.
They must enable client applications to access the content of a selected SNOMED CT versioned edition.
They should also enable access to extended versioned editions that include additional modules compatible with the selected edition.
They must provide access to data identifying which versioned edition (or extended versioned edition) is currently being accessed.
Terminology service users must ensure that the services they procure can be configured to access the SNOMED CT versioned editions (or extended editions) required by their organization, specialty, or national authority.
Healthcare application providers must ensure that applications:
Support access to configurable terminology services that can provide the required editions.
Track the history of the edition or extension in use, since this may affect data interpretation and analysis.
A SNOMED CT edition is a complete set of SNOMED CT components and reference set members that either belong to an identified module, or to one of the modules on which that module depends.
Notes on Editions
The module that defines the scope of an edition is called the focus module.
All editions (except the International Edition) combine one or more extension modules with the International Edition.
A complete edition may be prepared and released by SNOMED International, a National Release Center, or an Affiliate.
Dependencies between modules are recorded in the Module Dependency Reference Set.
Editions can be identified using a Uniform Resource Identifier (URI) as defined in the URI Standard.
Edition Types
International Edition
The set of SNOMED CT components and reference set members that belong to the International focus module or its dependencies.
Includes foundational content required by all other modules. The focus module is currently the SNOMED CT core module, with SNOMED CT model component module as a dependency. Can be supplemented by national or affiliate extensions.
Member / National Edition
A set of components and reference set members that belong to a focus module defined by a National Release Center (NRC) or its dependencies.
NRCs may produce multiple editions. Typically combines a national focus module with the International Edition and other required extensions. Distributed as part of a National Release.
Affiliate Edition
A set of components and reference set members that belong to a focus module created by an Affiliate Licensee with an allocated namespace, or its dependencies.
May extend the International Edition or a National Edition.
Extended Edition
A SNOMED CT edition to which additional modules have been added.
Used to add modules containing maps, subsets, or other derivatives. Dependencies must be satisfied. Additional modules may include reference sets, metadata concepts, and subtype relationships, but not new clinical concepts, descriptions, or relationships.
Versioned Edition
A SNOMED CT edition that is published on a specific date.
International releases occur twice a year (January and July). National extensions often follow, with some delays. Some extensions (e.g., medication-related) may release more frequently.
Extended Versioned Edition
A versioned edition with additional modules added.
Must satisfy all module dependencies. Additional modules may include reference sets, metadata concepts, and subtype relationships, but not new concepts, descriptions, relationships, or OWL members.
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