Imposing MetaAssociation Uniqueness
This prevents connecting several objects to the same object.
Example: To ensure that an org-unit is connected to a single tag, you must specify on the MetaAssociationEnd between Org-Unit and Tag that the MetaMultiplicity attribute is 0..1 or 1.
Uniqueness is applied particularly on sub-type and certain composition links.
Only the maximum MetaMultiplicity is taken into account to impose uniqueness of a MetaAssociation. The minimum MetaMultiplicity of a MetaAssociationEnd is purely for documentary purposes. It does not give an obligatory MetaAssociation.