Maintenance of an extension is essential to ensure that the extension continues to meet emerging user requirements, and remains aligned with updates to the International Edition of SNOMED CT (and any other extension on which it depends). As illustrated in below, the extension maintenance period begins when a new version of the extension is published and ends when the next version of the extension is published. As such, there is a continuous cycle of maintenance.

Two key maintenance tasks should be performed by an extension producer:

• Collecting and processing changes requested by terminology consumers
• Aligning the extension to new versions of the International Edition or other extensions on which it depends

These two maintenance tasks are explained further in 5.7.2 Change Requests and 5.7.1 Change Management respectively.

Extension Release Cycle

Regular updates to SNOMED CT are essential to satisfy emerging user requirements and to improve the quality of SNOMED CT itself. An extension producer must be aware that changes in the International Edition (or another extension on which the producer's extension depends) may have an impact on their extension. Therefore, the extension should be reconciled with the International Edition (and other associated extensions) every time a new release becomes available.

The International Edition of SNOMED CT is currently released twice a year - on January 31st and July 31st. Prior to each release of the International Edition, National Release Centres have an opportunity to evaluate the pre-production releases and plan their extension reconciliation strategy. Once the International Edition has been officially released, reconciliation of the extensions based on the new release can begin. Once complete, it is recommended that extension producers allow plenty of time for an alpha and/or beta version of their extension to be validated by their users before the new release is officially published. See 5.6.1.4 Preproduction Releases for more information.