REDEFINE in COBOL

The REDEFINES clause allows developer to use already declared for data description entries computer storage area for different data description entries.

1)     IDENTIFICATION DIVISION.
       PROGRAM-ID. REDIFN1.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 GRP1.
         05 WS-A PIC X(3) VALUE 'IBM'.
       01 GRP2 REDEFINES GRP1.
         05 WS-B PIC X(10).
       PROCEDURE DIVISION.
           MOVE 'MAINFRAME' TO WS-B
           DISPLAY WS-A
           DISPLAY WS-B
           STOP RUN.

2)     IDENTIFICATION DIVISION.
       PROGRAM-ID. REDIFN2.
       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01 WS-A PIC X(3) VALUE 'IBM'.
       01 WS-B REDEFINES WS-A PIC X(10).
       PROCEDURE DIVISION.
           MOVE 'MAINFRAME' TO WS-B
           DISPLAY WS-A
           DISPLAY WS-B
           STOP RUN.