SFLRCDNBR is used
1. to make sure that a particular subfile record is included in the screen display when it is shown (so that the user doesn’t have to press page-up or page-down to find the record)
2. to place the cursor on a particular subfile record. with the keyword (CURSOR)
Real world — returning to display an error you would want the Subfile record in error on the screen and the cursor on the record.
Anther real world — growing subfile. User pressed page-down subfile had 10 records and your program adds 10 more. You would want the cursor located on record 11 when the subfile is redisplayed.