Regions
Regions are customer-defined geographical areas that can be associated
to documents as metadata. Regions are configured with the
Region (mvn__Region__c) custom
object and can be configured as a hierarchy through associations to
other regions and
countries (mvn__Country__mdt). For example, the North
America region might have three child regions: Canada, Mexico, and
United States.
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Document regions (CM_Document_Region__c) connect regions and document
versions. A validation rule ensures that a Document Region can only be
created if it looks up to a Region and a Document Version. For a list of
Document Region fields, visit
Document Region.

To add region as document metadata to layouts, use the CM_Region
field. This field an internal system field and should not be modified in
any way. Visit Layout configuration.