Cardinal

The Cardinal datatype is an Enumerated type that indicates the cardinality of a property in a schema.

It has the following possible values:

1. 1 - Exactly one instance of the property is required.
2. 0..1 - Zero or one instance of the property is allowed.
3. 0..n - Zero or more instances of the property are allowed.
4. 1..n - One or more instances of the property are required.