SNOMED CT content in the International Edition is organized into two top level folders according to the release file types - Full and Snapshot. When packaging extensions and editions, this should be done using the same folder structure. Note that extension producers are only required to include the full release type for the extension. The snapshot release is optional, because it can be calculated from the full release. However, distribution of both release file types is recommended to simplify use by terminology consumers.
Each release file type has the same nested folder structure, with the following two subfolders:
The following recommendations apply to the structure and format of SNOMED CT release packages:
The recommended folder structure is illustrated below.
|General Release Folder Structure||Example - International Release|
SNOMED International provides templates to support extension producers in proper packaging of the release files. These templates detail the minimum expected set of files for each release product, plus the folder structure in which they should be packaged. For more information and to download these templates, please refer to https://confluence.ihtsdotools.org/display/RMT/Release+Package+Templates
Two main approaches to packaging exist:
The approach that is best for a given situation will depend on the content of the extension and the requirements of the consumers of the extension. The following subsections discuss each approach.
The figure below illustrates the idea of packaging as an extension. In this approach, the extension content is released in a separate package, which is not intended to be used on its own. Instead, the contents of the extension package must be combined with other packages (including the international release) by the terminology consumer. To determine which packages must be combined, the module dependency reference set is used to identify the dependencies for a given SNOMED CT edition (based on its focus module).
In the example below, the national content and local content have each been packaged as extensions. A terminology consumer must therefore combine the Local Extension package, the National Extension package and the International Edition package to achieve a complete terminology solution. Note that each package uses the same folder structure.
Figure 126.96.36.199-1: Creating a SNOMED CT Edition from extension packagesExtension producers choosing this packaging approach may package the content of the extension into release files in a variety of ways, including:
All content for a particular type of component (e.g. Concept) that is maintained by the extension producer is released in a single file. Components in this file may have different moduleIds, where the content has been authored in separate modules. Please note that where descriptions are authored in more than one language, these are generally included in separate files, with the applicable language code included in the file name.
All content for a particular type of component (e.g. of type Concept) is included in a set of files, with each file using a single moduleId.
Extension packaging may be appropriate when the content has the following characteristics:
The figure below illustrates the idea of packaging as an edition. In this approach, the package can be used on its own, without the need to combine with other packages.
When packaging an extension as an edition, the extension content is combined with the International Edition (and any other module on which the extension depends), in the standard folder structure. All content of a particular type is included in a single file, irrespective of the module it belongs to or the organization responsible for maintaining it. Care should be taken not to modify, add to or remove content that belongs to a module maintained by another organization. For more information please refer to authoring extensions.
Figure 188.8.131.52-2: Packaging an extension as an editionEdition packaging may be appropriate when the content has the following characteristics:
Files in an extension should be named in accordance with the SNOMED CT file naming convention. The file naming convention can simplify implementation and provide the following benefits:
A consistent naming convention across the International Edition and each National Edition
A standard way to identify the source and namespace by which a release file is managed
A mechanism to identify the type of information stored in a release file (e.g. documentation, tooling, etc.)
Guidance on file naming for release files in non-English extensions
Assurance that names will be unique across all editions and extensions over time
Quality assurance checks, which ensure that the naming convention has been applied, should be performed as part of the release process. For more information please refer to 2.1.2. Release File Naming Convention.