The output element gives a list of result values and internal results such as confidences or probabilities that can be computed by the model.
The univariate statistics contain global statistics on (a subset of the) mining fields.
This information is not directly needed by a PMML consumer, but in many cases it is helpful for maintenance and visualization of the model.
A PMML compliant system is not required to provide model selection by name.
The list of mining models in a PMML document may even be empty.
The document can be used to carry the initial metadata before an actual model is computed.
A PMML document containing no model is not meant to be useful for a PMML consumer.