Default Dataset is the most reliable set of products
associated to a given observation.
The "Default Dataset" can be: The best Highly Processed
Data Products (HPDP) associated to the observation
or the Off-Line Processing Pipeline v10.1 products.
When the "Default Dataset" is one of the HPDPs available
you will get different kind of products, basically FITS
and/or ASCII files which are the final result of processing
the observation beyond the pipeline.
The "Default Dataset" can be also the Off-Line Processing
Pipeline v10.1 products, mainly when HPDPs are not available
for the observation. In this case, the products delivered
under the "Retrieve Default Dataset" option are the Pipeline
"Fully Processed" and "Quick Look" products.