Like a CICS®-maintained data table, a user-maintained data table is loaded when the file is opened. However, unlike a CICS-maintained data table, the global user exit XDTRD can be used to both select and modify the records from the source data set that are included in the data table.
The user exit XDTAD can be used to select the records that are added to the table after initial loading. This user exit cannot modify the records because, as the records are written by the application, it is assumed that they are already in the format used in the data table.
If you are using these user exits, you should ensure that the user exits are activated before the file is opened.
For information about writing user exits, see Customizing data tables using user exits. For information about activating user exits, see Activating user exits for data tables.