# cardinality in group constraint

## cardinality in group constraint

**This is a synonym for attribute in group cardinality constraint.**

## attribute in group cardinality constraint

A constraint on the number of times that a specific attribute may be included in the same attribute group.

#### Notes

* Constraints on *attribute in group cardinality* apply only to non-redundant attributes. A redundant attribute is an attribute with a value that is subsumed by another attribute in the same group.
* Cardinality constraints are represented by square brackets containing a minimum value value represented as an integer, optionally followed by two dots and a maximum value represented as an integer or as an asterisk \*\*\*\*\*.
  * If the maximum is omitted then the maximum cardinality is the same as the minimum cardinality.
  * If the maximum is an asterisk \*\*\*\*\* the maximum cardinality is unlimited.
* *Attribute in group cardinality* is NOT the same as attribute group cardinality constraint.

Attribute group cardinality constraint is defined as:

```
* A constraint on the number of times that an attribute group may be included in the same concept definition or expression.
```

\_\_

#### Examples

* 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.

< [404684003 |Clinical finding|](http://snomed.info/id/404684003) :\
{\[0..1] [363698007 |Finding site|](http://snomed.info/id/363698007) = < [91723000 |Anatomical structure|](http://snomed.info/id/91723000) }

* 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.

< [404684003 |Clinical finding|](http://snomed.info/id/404684003) : \[2..\*] [363698007 |Finding site|](http://snomed.info/id/363698007) = < [91723000 |Anatomical structure|](http://snomed.info/id/91723000)

* A clinical finding could satisfy both the above constraints by have two or more groups each of which contains one finding site.

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