> For the complete documentation index, see [llms.txt](https://docs.b2ihealthcare.com/snow-owl-authoring-platform/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.b2ihealthcare.com/snow-owl-authoring-platform/concept-model/machine-readable-concept-model/concept-model-constraints.md).

# MRCM domain members

MRCM domains are represented by members in MRCM domain reference set type reference sets. The referenced component of a domain member is selected as the most descriptive concept of the set of concepts defined by its Domain constraint.

Its domain constraint can be described by an ECL expression.

The referenced concept is used to link the domain definition to its allowed attributes in the MRCM attribute domain type reference sets.

<figure><img src="https://content.gitbook.com/content/N7ynFOLTw3W9Zow9AaAJ/blobs/XSu2iZLBlLwKEsBpAZVs/image.png" alt=""><figcaption><p>MRCM domain members</p></figcaption></figure>

For more information regarding MRCM domain members see the [official documentation](https://confluence.ihtsdotools.org/display/DOCMRCM/5.1+MRCM+Domain+Reference+Set).