Resources & Documentation
Learn more about ECL and SNOMED CT
ECL Operators Quick Reference
These are the core operators used in Expression Constraint Language. Click on any operator to see it used in the Query Builder.
<
Descendants of
All subtypes, excluding self
<<
Descendants or self
All subtypes, including self
>
Ancestors of
All supertypes, excluding self
>>
Ancestors or self
All supertypes, including self
<!
Children of
Direct subtypes only (1 level)
>!
Parents of
Direct supertypes only (1 level)
^
Member of
Concepts in a reference set
*
Any concept
Wildcard - matches anything
:
Refinement
Filter by attributes
=
Equals
Attribute value constraint
AND
Conjunction
Must match both constraints
OR
Disjunction
Match either constraint
ECL Specification
Official Expression Constraint Language specification from SNOMED International. The definitive guide to ECL syntax and semantics.
View DocumentationECL Examples
Extensive examples of ECL expressions from simple to complex, directly from the official specification.
Explore ExamplesQuick Reference
Handy quick reference guide for ECL syntax and operators. Perfect for when you need a quick reminder.
View ReferenceSNOMED CT Browser
Browse the SNOMED CT terminology to find concept IDs, explore hierarchies, and understand relationships.
Open BrowserSNOMED International
Official SNOMED International website with resources, news, and information about membership and licensing.
Visit SiteOntoserver
Learn about the Ontoserver FHIR terminology server that powers this application's queries.
Learn MoreAdditional Learning Resources
SNOMED CT E-Learning
Free online courses covering SNOMED CT fundamentals, including ECL.
Access E-LearningSNOMED Forums
Community forums for asking questions and discussing SNOMED CT implementation.
Visit ForumsSNOMED CT Compositional Grammar
Learn about the related syntax for representing SNOMED CT expressions.
View SpecificationFHIR Terminology Services
HL7 FHIR specification for terminology operations including ValueSet expansion with ECL.
View FHIR SpecAustralian Medicines Terminology
Information about AMT and how it relates to SNOMED CT drug concepts.
Learn About AMTAbout the Terminology Server
CSIRO Ontoserver (FHIR R4)
https://r4.ontoserver.csiro.au/fhir
This application uses the public CSIRO Ontoserver instance, which supports:
- SNOMED CT International Edition
- Australian Medicines Terminology (AMT)
- FHIR R4 terminology operations
- ECL query expansion via ValueSet/$expand
This is a public demo server. For production use, consider setting up your own Ontoserver instance or using a licensed terminology service.