Expression Constraint Language (ECL) is a formal syntax for representing SNOMED CT expression constraints. Expression constraints are computable rules used to define bounded sets of clinical meanings represented by either precoordinated or postcoordinated expressions.
Snow Owl includes an editor and execution environment for ECL. All of the operators and grammar constructs defined in the Expression Constraint Language specification are supported. Using ECL, you can query concepts by their relationships as opposed to their human-readable descriptions.