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Given the RF2's history tracking capability, it is possible to perform a number of different releases of content:

Table 2.8-1: SNOMED CT Release Types

Release type



A full release is a release type in which the release files contain every version of every component ever released.


A snapshot release is a release type in which the release files contain one version of every component released up to the time of the snapshot. The version of each component contained in a snapshot is the most recent version of that component at the time of the snapshot.


A delta release is a release type in which the release files only contain rows that represent  component versions and   reference set member versions created since an identified previous release date. 


  1. Each row in a delta release file represents either a new  component or reference set member or a change to an existing component or reference set member since the identified previous release date.
  2. A delta release identifies difference between two versions of the same release package. A delta release added to the  full release for the "identified previous release date" is identical to the  full release for the new version.
  3. The "identified previous release date", on which a delta release is based, is usually the most recent previous release release. However, that may not always be the case. For example, where interim releases are made between two major releases there may be a combined delta release covering a period since a previous major releases

There are valid use cases for each type of Release Type. Each International release will incorporate all three of these Release Types, allowing users to choose the most appropriate format for their needs.

A full release will always be available from release centers. Optionally, other Release Formats may also be made available. Where out of cycle releases are made, these will follow the same format as standard cycle releases.