This section covers several general topics related to SNOMED CT release files including:
This section covers several general topics related to SNOMED CT release files.
3. Component Release Files Specification
Files that represent the main SNOMED CT components:
Concepts
Descriptions
- Relationships
4. Reference Set Release Files Specification
Files that customize and enhance SNOMED CT by representing:
- Subsets of concepts and descriptions
- Maps to other code systems
- Language and dialect preferences for different terms
- Annotation of components
- Associations between components
- Other forms of configuration and extensibility
The Terminology Services Guide is a separate document that includes guidance on Representing Terminology Data and Importing SNOMED CT Release Files.
Historical Note on Current and Previous Release File Formats
The standard format in which SNOMED CThas been distributed since 2012 is known as Release Format 2(RF2). It was developed in response to extensive feedback on the original release file format, now known as Release Format 1(RF1), in which SNOMED CTwas distributed between its first release in 2002 and 2012. The SNOMED CT International Edition is no longer distributed in RF1. However, a conversion tool to general RF1 style files from the RF2 release files was made available during a transition period.
The key enhancements in RF2were:
- More robust and consistent version representation;
- Inclusion of a moduleId and module dependency mechanism, which together enable modularization of releases while representing dependencies between modules;
Reference setsto provide an extensible and versionable way to configure SNOMED CT.Including support for subsets, maps, annotations, alternative hierarchies, etc.;
Use of an added hierarchyto represent metadata about the structure of SNOMED CTitself.
In common with the earlier release format RF2specifies files that:
- Represent the components of SNOMED CT: (concepts, descriptions and relationships)
Provide standard representations for subsets, language preferences and maps to other codes and classifications.
- Are distributed as tab-delimited text files - which represent character content in accordance with the Unicode UTF-8 specification;
Use SNOMED CT Identifiersas the permanent Identifierof released core components;
Support extensionsto the International Releaseusing namespacesallocated to licensees to denote the provenance of added components and to ensure Identifieruniqueness.
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