5.2. Release Format 2 - Introduction

This section describes the revised release file structure of SNOMED CT ^®. This file structure is referred to as Release Format 2 ( RF2) to distinguish it from the original Release Format ( RF1) in which SNOMED CT has been distributed since its first release in 2002.

The Release Format 2 specification is divided into two parts. The RF2 Core Component Guide is concerned with the representation of the Concepts, Descriptions and Relationships that contain the primary content of SNOMED CT. The RF2 - Reference Sets Guide specifies the common extensible pattern that is used to add additional information related to the core components. It also describes the ways in which this pattern is used to represent essential functionality (such as language specificity, historical status changes and associations) and optional additional functionality (including subsets, cross mapping and alternative navigation hierarchies).

Files that conformed to the RF2 specification were available as technology preview during 2010 and early 2011 to enable practical testing of this format. The results of feedback from that testing process have been incorporated into the specification. RF2 distribution files are available for the current International Releases of SNOMED CT and these files also contain the full history of all previous releases. During 2012 RF2 will become the primary Release Format for SNOMED CT. Implementers requiring data in the RF1 format during a transitional period will be supported by use of conversion application developed by the IHTSDO.