Records are loaded into an entry-sequenced data set regardless of the contents of the records. The sequence is determined by the order in which the records are received to be placed in the data set. This is what determines the physical arrangement. New records are stored at the end of the data set.

A checkpoint cannot be taken if a VSAM entry-sequenced data set is open for output with an immediate-upgrade path (or alternate index) open over it, unless the no-reposition option, AMP='CROPS=NRE’ or AMP='CROPS=NRC’, is specified. VSAM immediate-upgrade data sets are key-sequenced data sets, and repositioning is not supported for them.

For a VSAM entry-sequenced output data set, all data added after the last checkpoint was taken is physically erased by restart unless the AMP='CROPS=NRE’ or NRC subparameter is specified in the DD statement for the data set. If data is erased by restart, the catalog record for the data set is updated to reflect the current end of data, and the data set statistics are adjusted to reflect the new status.

During restart, entry-sequenced output data sets are restored by the elimination of all records added at the end since the checkpoint.