VALUE, REDEFINES, RENAMES & 88 Levels

Figurative constants: ZERO/ZEROS/ZEROES, SPACE/SPACES, HIGH-VALUE(S) (highest collating character, X'FF'), LOW-VALUE(S) (X'00'), QUOTE(S), ALL literal, NULL (pointers).

10.1 VALUE

Figurative constants: ZERO/ZEROS/ZEROES, SPACE/SPACES, HIGH-VALUE(S) (highest collating character, X'FF'), LOW-VALUE(S) (X'00'), QUOTE(S), ALL literal, NULL (pointers).

Constants: COBOL 2002 defines 01 CON-MAX-ROWS CONSTANT AS 100. (supported by GnuCOBOL, which also accepts the Micro Focus 78 level); in IBM code, constants are usually ordinary items with VALUE that are never modified.

01  WS-COMPANY        PIC X(20)    VALUE "ACME CORP".
       01  WS-RATE           PIC V999     VALUE .075.
       01  WS-MAX-ITEMS      PIC 9(4)     VALUE 500.
       01  WS-LINE           PIC X(80)    VALUE ALL "-".
       01  WS-BLANKS         PIC X(10)    VALUE SPACES.
       01  WS-ZERO-AMT       PIC S9(5)V99 VALUE ZERO.
       01  WS-HIGH           PIC X(5)     VALUE HIGH-VALUES.

10.2 REDEFINES

REDEFINES gives the same storage a second description. Common uses: viewing a date as parts, overlaying record types, or initializing a table with literals.

Rules: the redefining entry must immediately follow the redefined one at the same level; it must not be larger than the original at the 01 level in older compilers (GnuCOBOL and IBM allow a larger redefinition at level 01 in WORKING-STORAGE but warn); VALUE is not allowed in a redefining item (except 88 levels).

01  WS-DATE-NUM               PIC 9(8).
       01  WS-DATE-PARTS REDEFINES WS-DATE-NUM.
           05  WS-YEAR               PIC 9(4).
           05  WS-MONTH              PIC 99.
           05  WS-DAY                PIC 99.

      * Multiple record types in one file record
       01  TRANS-RECORD.
           05  TRANS-TYPE            PIC X.
           05  TRANS-DATA            PIC X(79).
           05  TRANS-ADD REDEFINES TRANS-DATA.
               10  ADD-CUST-ID       PIC 9(6).
               10  ADD-CUST-NAME     PIC X(30).
               10  FILLER            PIC X(43).
           05  TRANS-PAY REDEFINES TRANS-DATA.
               10  PAY-CUST-ID       PIC 9(6).
               10  PAY-AMOUNT        PIC S9(7)V99.
               10  FILLER            PIC X(64).

10.3 RENAMES (level 66)

66 entries come immediately after the record they rename. RENAMES is rarely used in new code — REDEFINES or a group item is usually clearer.

01  EMPLOYEE-REC.
           05  EMP-ID                PIC 9(5).
           05  EMP-FIRST             PIC X(15).
           05  EMP-LAST              PIC X(20).
           05  EMP-DEPT              PIC X(4).
       66  EMP-FULL-NAME RENAMES EMP-FIRST THRU EMP-LAST.
       66  EMP-KEY       RENAMES EMP-ID.

10.4 88-level condition names

88 levels make conditions self-documenting and keep magic values in one place — use them for every flag and code.

01  WS-MARITAL-STATUS         PIC X.
           88  SINGLE                VALUE "S".
           88  MARRIED               VALUE "M".
           88  DIVORCED-OR-WIDOWED   VALUE "D" "W".
           88  VALID-STATUS          VALUE "S" "M" "D" "W".

       01  WS-SCORE                  PIC 999.
           88  GRADE-A               VALUE 90 THRU 100.
           88  GRADE-B               VALUE 80 THRU 89.
           88  FAILING               VALUE 0 THRU 59.

       01  WS-EOF-SWITCH             PIC X VALUE "N".
           88  END-OF-FILE           VALUE "Y"
                                     WHEN SET TO FALSE IS "N".

IF MARRIED
               DISPLAY "Married"
           END-IF
           IF NOT VALID-STATUS
               DISPLAY "Invalid status code"
           END-IF
      *    Moves "Y" to WS-EOF-SWITCH:
           SET END-OF-FILE TO TRUE
      *    Moves "N" (requires the WHEN SET TO FALSE clause):
           SET END-OF-FILE TO FALSE