First announced in 2019 with engagement and consultation by SNOMED International’s Modeling Advisory Group, the organization proposed an enhancement to SNOMED CT by adding the capability to express Concrete Domain values.  This change is an enhancement to SNOMED CT's logic features and will increase the flexibility of SNOMED CT primarily to express numeric values.
This enhancement will initially target improvements in the Pharmaceutical / biologic product hierarchy.  This feature will be used to better express strengths and concentrations of clinical drugs as well as ingredient counts, specifically supplying clinical drug strengths as true numbers, rather than using the existing work-around of concepts which represent those numbers.
Why is this important? 
SNOMED International is driven to make SNOMED CT richer, more precise and more useful to its global users.  Presently, this can be limited when particular types of information cannot be fully represented using the existing SNOMED CT RF2 release distribution format.  With the case of numbers, for example the weight of a particular medicinal substance used in a drug product, it is desirable to be able to represent that amount, and then be able to ask questions like "List all drugs that contain >= 100mg of Paracetamol, or Acetaminophen".
Technical preview details
Concrete Domain changes are currently slated to appear in the next SNOMED CT International Edition release in July 2021.  This will impact inferred relationship file changes and stated axiom file changes to the RF2 package, along with making additional features available in the International Edition.
Prior to this transition, a technical preview of proposed Concrete Domain changes have now been published in line with the recent January 2021 International Edition and contain drug concept strengths and counts expressed as concrete values in a new Relationships file. 
This technical preview is a full RF2 International Edition package (as opposed to a standalone Delta file containing Concrete Domains), containing all International content in addition to new Concrete Domains.  The purpose of the technical preview is to provide an advanced look at the final Release package slated for July 2021 to help our community evaluate their tooling, systems and release processes.
Details of the proposed technical changes can be accessed in the linked release notes.

The Tech Preview release package is distributed for evaluation purposes only.  It must not be used in production clinical systems or in clinical settings, or distributed to Affiliate Licensees or any third parties at this time.  
With the release of this technical preview, please be aware that the Concrete Domains proposal is still in the consultation stage. Changes may still be made before the planned final solution moves to Production in July 2021.

How do I access the Concrete Domain technical preview or additional information? 
For additional information on the planned transition to Concrete Domains, please visit the resources listed below or email  Any feedback on the technical preview release files are requested as early as possible, but before April 15th, 2021.


Access the technical preview

Access the technical preview via MLDS (Login required for access)

Technical preview release notes

View the technical preview via the SNOMED CT browser

Schedule of planned changes

Scheduled changes: "Concrete Domains and Numeric Representation”