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Release Format 2 (RF2) is the current release format developed by the International Health Terminology Standards Development Organisation (IHTSDO) to support the creation of reference sets. This has replaced Release Format 1 (RF1).
 
On Wednesday, 28 October 2015, the IHTSDO General Assembly voted to approve the deprecation of SNOMED CT Release Format 1 (RF1). July 31, 2016 (International) and September 1, 2016 (US Edition) is the last time SNOMED CT was distributed in RF1. SNOMED CT will only be distributed in RF2 format. The key enhancements in RF2 are:

  • More robust and consistent version representation;
  • Reference sets, provides a more easily extensible and maintainable replacement for RF1 subsets and cross maps;
  • Use of an added hierarchy to represent metadata about the structure of SNOMED CT itself. 

The RF2 release represents:
 
The components of SNOMED CT:

  • Concepts
  • Descriptions
  • Relationships 

Additional derivatives that provide standard representations of:

  • Value-sets consisting of a specified set of concepts or relationships;
  • Cross mapping tables to other codes and classifications;
  • Support for extensions to the SNOMED CT International Edition using namespaces allocated to licensees to denote the provenance of added components and to ensure Identifier uniqueness. 

The RF2 release file is provided in:

  • Tab-delimited text files;
  • Unicode UTF-8 specification.