An unload data set will have a format different from a partitioned data set or a PDSE, no matter if the data set is being stored on a DASD device or on tape. Its records will be longer and may require more space. It will have sequential organization. You cannot always treat an unload data set the same as you would the original partitioned data set or PDSE.

It may be easy to confuse the unload data set, which is sequential, from the partitioned data set or PDSE. The unload data set or container data set is the sequential data set created by the unload operation. The unloaded data set is the original partitioned data set or PDSE that was unloaded into the unload data set.