Recently in an interview asked a question about 66 Level. This is simple question, but very rarely used this level in real time.
So, 66 Level will be used to rename a group of elements. Let me show an example,
A level-number of 66 is used to declare a re-grouping of previously defined items, irrespective of how those items are structured.
01 customer-record. 05 cust-key PIC X(10). 05 cust-name. 10 cust-first-name PIC X(30). 10 cust-last-name PIC X(30). 05 cust-dob PIC 9(8). 05 cust-balance PIC 9(7)V99. 66 cust-personal-details RENAMES cust-name THRU cust-dob. 66 cust-all-details RENAMES cust-name THRU cust-balance.
The “cust-personal-details” is a new group name to the customer-record. So the new group name will NOT take additional space, it uses the original group name space.