In order to expose the format and data structure of the ResultContent, it is not possible to subtype the ResultDataType, as the type of a structure field cannot be changed in a subtype. However, a subtype of the ResultType VariableType should be created, where the ResultContent and ReducedResultContent can be overridden and the DataType is changed to the specific DataType. In order to expose this for the Event subscriptions, a subtype of the ResultReadyEventType should be created as well, using the subtype of the VariableType.
That is, without a subtype of the VariableType there is no standardized mechanism to expose the expected DataType for ResultContent and ReducedResultContent. Clients need to receive an instance of ResultDataType in order to get the information about the used DataType in that instance.