Level 88 - Complex Business Logic Simplification

"You're refactoring a legacy payment processing program with 3,000 lines of spaghetti code. You find this pattern repeated 50+ times:

IF TRAN-CODE = 'CHK' OR TRAN-CODE = 'ACH' OR 
   TRAN-CODE = 'WIR' OR TRAN-CODE = 'EFT'
    PERFORM ELECTRONIC-PAYMENT
ELSE
  IF TRAN-CODE = 'CSH' OR TRAN-CODE = 'MNY'
    PERFORM CASH-PAYMENT
  ELSE
    IF TRAN-CODE = 'CRD' OR TRAN-CODE = 'DEB'
      PERFORM CARD-PAYMENT
    ELSE
      PERFORM ERROR-HANDLING
    END-IF
  END-IF
END-IF.

Business rules:

• Electronic: CHK, ACH, WIR, EFT, RTG (new), FED (new)
• Cash: CSH, MNY
• Card: CRD, DEB, CCP (new)
• Rules change quarterly (new codes added)

Redesign using Level 88. Show before/after code and explain maintainability benefits."

• Advanced COBOL techniques
• Code maintainability awareness
• Understanding of condition names
• Ability to simplify complex logic

1. Refactored Data Division:

01  TRAN-DETAILS.
    05  TRAN-CODE           PIC X(3).
        88  ELECTRONIC-TRAN VALUE 'CHK' 'ACH' 'WIR' 
                                   'EFT' 'RTG' 'FED'.
        88  CASH-TRAN       VALUE 'CSH' 'MNY'.
        88  CARD-TRAN       VALUE 'CRD' 'DEB' 'CCP'.
        88  VALID-TRAN      VALUE 'CHK' 'ACH' 'WIR' 
                                   'EFT' 'RTG' 'FED'
                                   'CSH' 'MNY' 'CRD' 
                                   'DEB' 'CCP'.

2. Simplified Procedure Division:

EVALUATE TRUE
    WHEN ELECTRONIC-TRAN
        PERFORM ELECTRONIC-PAYMENT
    WHEN CASH-TRAN
        PERFORM CASH-PAYMENT
    WHEN CARD-TRAN
        PERFORM CARD-PAYMENT
    WHEN OTHER
        PERFORM ERROR-HANDLING
END-EVALUATE.

3. Benefits Explained:

• Maintainability: Add new codes in one place (data division)
• Readability: Self-documenting code (ELECTRONIC-TRAN vs. multiple ORs)
• Testing: Easier to verify all valid codes covered
• Performance: Compiler optimizes Level 88 conditions
• Error reduction: Can't forget to add code in one place and miss others

4. Advanced Usage:

* Validation
IF NOT VALID-TRAN
    PERFORM ERROR-HANDLING
END-IF.

* Setting values
SET ELECTRONIC-TRAN TO TRUE  * Sets TRAN-CODE to 'CHK'

5. Maintenance Process:

• When new code added: Update Level 88 definition only
• All 50 instances automatically updated
• No risk of missing one instance

• ❌ Just reduces nested IFs without using Level 88
• ❌ Doesn't understand SET verb with Level 88
• ❌ Can't articulate maintainability benefits
• ❌ Doesn't mention testing or validation improvements

• "Can you have multiple Level 88s for the same field?"
• "What happens if you SET ELECTRONIC-TRAN when TRAN-CODE already has 'CRD'?"
• "How would you test that all valid transaction codes are covered?"
• "What if transaction codes need hierarchy (ELECTRONIC-TRAN includes DOMESTIC-TRAN and INTL-TRAN)?"