# FAQs

* [What is the Expression Constraint Language (ECL)?](https://docs.snomed.org/snomed-ct-user-guides/snomed-ct-browser-guide/faqs/the-expression-constraint-language-ecl)
* [What is the Machine Readable Concept Model (MRCM)?](https://docs.snomed.org/snomed-ct-user-guides/snomed-ct-browser-guide/faqs/the-machine-readable-concept-model-mrcm)

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