Cardinality allows a block of properties to be re-instantiated within a list of properties. It refers to the property allowing dynamic multiplication of a block within the scope of the property values to be managed. Within the contents of data description, cardinality is therefore a means to determine the number of identical blocks.
Cardinality defines the relationship between a cardinality property (of type number), and a property (of type set of class_instance type) which refer to the classes which are re-instantiated. The value of a cardinality property is a positive integer. For zero set of instanced classes is empty. How to create change requests for cardinality is described here.
EXAMPLE: The block “Process connection” contains a repeatable block “End connection”. The cardinality property is “number of end connections”, see the following figure:
Creating the description of a concrete object, the value assigned to “number of end connections” property has been set to “2”. As a result the “end connection” reference property together with the associated block of properties appears twice in the list of properties. By setting the value of the property “Designation” to “Upstream” in the first block and “Downstream” in the second, the two end connections to be found on the device can be described.
In the case of the example “car”, one could use cardinality to describe the doors. For instance, the properties colour, door type, and electric window levers describe the doors. A „door properties“ block combines these properties, which can be assessed at random using the reference property “number of doors”. When we wish to describe a 3-door vehicle, we will have to set the reference property “number of doors” to“3”. As a result, the block “door” is accessed 3 times.