A constraint on the number of times that a specific attribute may be included in the same attribute group.
Attribute group cardinality constraint is defined as:
The following expression constraint restricts cardinality in-group and would require a clinical finding whose definition has no more than one finding site in each group. However, it permits multiple groups to exist as there are cardinality constraints on the group.
In contrast, the following expression constraint is satisfied by any clinical finding whose definition has two or more non-redundant finding sites, irrespective of the attribute group in which they are contained.
A clinical finding could satisfy both the above constraints by have two or more groups each of which contains one finding site.