> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-specifications/snomed-ct-release-file-specification/component-release-file-specification/4.2-file-format-specifications/metadata-files.md).

# Metadata Files

## "release-package-information.json" file

These files are located in the top-level directory of the SNOMED CT Release packages, and contain various information related to the specific Release package in which they reside.

**release-package-information-.json file - Detailed Specification**

<table><thead><tr><th width="230.17498779296875">Field</th><th width="140.21875">Data Type</th><th>Purpose</th></tr></thead><tbody><tr><td>effectiveTime</td><td>String</td><td><p>Specifies the inclusive date at which the package has been versioned</p><p><strong>Note</strong> : In distribution files the effectiveTime should follow the short ISO date format (<em>YYYYMMDD</em>)</p></td></tr><tr><td>previousPublishedPackage</td><td>String</td><td>The name of the last Release package to have been published for this specific SNOMED CT Product</td></tr><tr><td>licenceStatement</td><td>String</td><td>The licence statement that applies to this particular version of the Product, and which must be adhered to when using the package.</td></tr><tr><td>languageRefsets</td><td>String</td><td>Details of all language refsets included within the package (eg)                                                                                <br><em>{</em><br><em>"id": "900000000000508004",</em><br><em>"term": "Great Britain English language reference set"</em><br><em>},</em><br><em>{</em><br><em>"id": "900000000000509007",</em><br><em>"term": "United States of America English language reference set"</em><br><em>}</em></td></tr><tr><td>packageComposition</td><td>String</td><td></td></tr><tr><td>      essentialComponents</td><td>String</td><td>Any information useful to the users, regarding  components that are a mandatory part of each version of the package. </td></tr><tr><td>      optionalComponents</td><td>String</td><td>Bespoke fields can be created in this section in order to provide users with any additional information that may be specific about this particular Product, especially in regard to components that might (but don't have to) be included in each version of the package.  See below for examples:   </td></tr><tr><td>                        <sub>MapDirectionality</sub></td><td><sub>String</sub></td><td><sub>States which direction each map file is mapped in (eg) <em>SNOMED to external product</em>, or <em>external product to SNOMED</em></sub></td></tr><tr><td>                   <sub>SNOMEDMapSource</sub></td><td><sub>String</sub></td><td><sub>The version of SNOMED CT that the map is based upon (eg) <em>SNOMED CT version 20250701, released July 2025</em></sub></td></tr><tr><td>                     <sub>externalMapSource</sub></td><td><sub>String</sub></td><td><sub>The version of the external product upon which the map is based (eg) <em>Orphanet version July 2025</em></sub></td></tr><tr><td>                                 <sub>dependency</sub></td><td><sub>String</sub></td><td><sub>The external product version upon which this package is dependent</sub> </td></tr><tr><td></td><td></td><td></td></tr></tbody></table>


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