SNOMED CT is more than a single code system. It has a core international edition, with additional optional derivatives, and many extension editions.

While this is a powerful mechanism that provides flexibility to those using SNOMED CT to extend the content to meet local demands and timeframes, it also creates a problem. There is no one place where all the codes in the SNOMED CT universe are held, so when a code is received that isn't known it can be hard to find out what it is. Similarly it can be hard for an extension builder to see what is in the other extensions to avoid duplication.

Ideally when codes are sent, the edition URI or even version URI is often provided. 

A change that could help is to refer edition URIs to somewhere sensible which will allow someone to discover where to get the content. For example the SNOMED CT-AU edition URI could refer to an appropriate place to get SNOMED CT-AU RF2 content and/or a terminology service to examine the data and/or a terminology browser. For example http://snomed.info/sct/32506021000036107/version/20170630 or http://snomed.info/sct/32506021000036107

But sometimes just the SNOMED CT scheme URI is provided is just http://snomed.info/sct.

Ideally there'd be a place where all known extensions of SNOMED CT can be pulled together, a "Universal Edition" of SNOMED CT. Additionally it would be very useful for this content to be loaded into a terminology server with a standard, rich API (for example a fairly complete FHIR terminology service implementation) and a browser which allows anyone to find out about a SNOMED CT identifier from anywhere in the SNOMED CT universe.

Use Case

Dealing with content spread across a range of editions.

Priority : Highly desirable.    ML "Universal content is highly desirable and cheap.   A universal 'Edition' would be much more expensive."   Notes that will be taken forward anyway with the work done by Rory's evolution working group.

Issues

• Merge conflicts / Managing "version skew".
• Quality issues in editions eg module dependency problems, rows failing to adhere to RF2 specification.

Suggested actions

1. make SNOMED CT URIs more useful by making them resolvable in collaboration with the extension owners
2. create a SNOMED CT "Universal Edition" by collecting the known extensions and making that available as a complete unit. By providing a standard technical mechanism to push extension releases to, extension builders could facilitate this universal edition by pushing their releases rather than a central effort to continuous pull/collect releases
3. make the Universal Edition available as an RF2 package for download
4. load the Universal Edition regularly into a suitable terminology server and make that available, ideally publicly
5. load the Universal Edition regularly into a terminology browser available, ideally publicly

Thoughts, comments, suggestions, objections?

Discussion

ML Suggested first step of creating a union of all concepts that have ever been defined.