The IDMS interface module DTLAMIDM supports the following types of keyed access:
CALC. The optimized read process uses CALC if all components of the CALC key include equals conditions.
System index. If CALC cannot be used, and the primary key column includes supported values for system index, the optimized read process uses system index reading.
VIA within a set. If the primary key cannot use optimized reading, an area sweep locates and retrieves IDMS records.