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The SNOMED CT Expression Constraint Language is a formal language for defining bounded sets of clinical meanings represented by either precoordinated or postcoordinated expressions.


SNOMED CT expression constraint language version 2.1 has been published at


SNOMED International is aware of the following implementations of the SNOMED CT Expression Constraint Language:

If you know of additional ECL implementations, please contact with details.


  1. Very nice to have this overview of implementations. With new versions of ECL emerging, it would be good to make clear which implementation supports which version of ECL.

    1. As well as which features of ECL are supported by each implementation.

  2. To all:

    Slang–the 3rd implementation on the list–was down, but I have restarted it.

    Sorry to those who tried to use it and failed–please try again! 

    Let me know if you have problems.


  3. Hello, could you please add to your list of implementations the one below, which is also referenced on Features of Known Servers

    PHAST's FHIR Terminology server STS: 

    This server is available 7/24 for testing, it is for instance testable through CSIRO's VSTool

    It is using basic authentication.

    1. Added. Thank you!
      Kind regards,