Describing a Sequential, VSAM, or ISAM Data Source

You can describe and report from sequential, VSAM, and ISAM data sources.

In a sequential data source, records are stored and retrieved in the same order as they are entered.

With VSAM and ISAM data sources, a new element is introduced: the key or group key. A group key consists of one or more fields, and can be used to identify the various record types in the data source. In the Master File representation of a data source with different record types, each record type is assigned its own segment.

For VSAM and ISAM data sources, you must allocate the Master File name to the CLUSTER component of the data source.

For information about updating VSAM data sources, see the Dynamic Private User Exit appendix in the Adapter Administration manual.