DataSetMetaData may be specific to a single Publisher and a single selection of information or universal e.g. defined by a standard organisation or by a plant operator as a DataSetClass. DataSets that conform to such a DataSetClass are identified with a DataSetClassId.
The DataSetClassId is the globally unique identifier (Guid) of a DataSetClass. It is included in the DataSetMetaData. The NetworkMessageContentMask controls the availability of the DataSetClassId in the NetworkMessage.