The cardinality value indicates if the metadata concept is mandatory or not, and the possible dimension. The value of “1” means that the metadata is mandatory. The value of “0:1” means that the metadata concepts are not mandatory, but in case information is provided, just one is allowed. The values of “0:N” and “1:N” allow several entries, where in the first case it is not mandatory to provide information, in the second one it is. “X” means that the metadata is not relevant to describe the model class.