An association between a set of attribute value pairs that causes them to be considered together within a concept definition or postcoordinated expression.
When an attribute group is represented as a group of defining relationships it is usually referred to as a relationship group.
| Cholecystectomy with exploration of common duct| has two different attribute groups:
is grouped with
is grouped with
If these attributes were not grouped, this procedure would incorrectly classified as a subtype of .
Relationship group
Role group