Basic System DMS PROC › SELECT Command › DSCL SELECT CRITERIA Field Name Descriptions › F1MODDT — Format-1 DSCB last modified date (date format)

F1MODDT — Format-1 DSCB last modified date (date format)

Comparison dates can be entered in any acceptable CA Disk format.
For all data set processing, the value F1MODDT is set to the location indicated by the CA Disk system parameter DSCBLMOD in the format-1 DSCB of each data set or VSAM component. For more details, see the system parameter description for DSCBLMODnnnk in the Systems Guide. Missing or invalid values are assigned a value of 00/00/0000 or 0. CA Disk or IBM does not set the last modified date in the format-1 DSCB of VSAM index components.

Under SCAN REALVOLS, the F1MODDT selection criteria will give increased performance over the MODDT selection criteria due to eliminating the need for CA Disk to access the catalog to retrieve the cluster name for VSAM components that do not meet this MODDT test.

The modification date in the format-1 DSCBs of components of VSAM clusters can provide different results compared to selection based on the modification date maintained in the cluster's catalog entry. Non-VSAM data sets are processed identically between MODDT and F1MODDT.

If you want to select VSAM clusters by the modification date in the cluster's catalog entry, while maintaining non-VSAM compatibility, use MODDT instead of F1MODDT. This selection criteria is only valid when using SCAN REALVOLS, it is ignored for SCAN CAT, unlike the MODDT selection criteria, which is valid for both. Another difference between F1MODDT and MODDT selection criteria is that F1MODDT can allow your CA Disk job to process more quickly. This is because F1MODDT is set up to allow CA Disk to bypass some catalog processing.

For more information, see Midnight "Rapid Aging" Problems.