Take your systemsforward.

Demo (fictional sample)This is not a customer project or real data. It uses an order discount calculation as the example.

1. STEP 1 / Original program

   ORDCALC.cbl (excerpt)

   A typical program that sets the order amount and status from quantity, unit price and customer rank.

   001100     MOVE ZERO TO WS-DISC-RATE.
   001200     IF IN-QTY >= 100
   001300         MOVE 0.05 TO WS-DISC-RATE
   001400     END-IF.
   001500     IF IN-CUST-RANK = 'A'
   001600         ADD 0.02 TO WS-DISC-RATE
   001700     END-IF.
   001800     COMPUTE OUT-AMOUNT ROUNDED =
   001900         IN-QTY * IN-UNIT-PRICE * (1 - WS-DISC-RATE).
   002000     IF OUT-AMOUNT > IN-CREDIT-LIMIT
   002100         MOVE '9' TO OUT-STATUS
   002200     ELSE
   002300         MOVE '0' TO OUT-STATUS
   002400     END-IF.

   Scroll sideways to see the whole program

2. STEP 2 / Business rules

   Four rules and one open question

   AI drafts the rules and an engineer confirms each one against the source lines. Unknowns are not filled in by guesswork.

   Four rules and one open question

   ID	Rule	Source lines
   R-01	Quantity of 100 or more: 5% discount	001200–001400
   R-02	Customer rank A: 2% more (up to 7%)	001500–001700
   R-03	Amount rounded to the nearest yen	001800–001900
   R-04	Over the credit limit: “on hold” (status 9)	002000–002400
   U-01	Approval and notification after a hold are not in this program	Open: decide with the customer

3. STEP 3 / Excel design spec

   ORDCALC_design_spec.xlsx

   Screen, processing and data specifications are delivered in a form you can edit. Each row keeps its source.

   • Overview
   • Inputs and outputs
   • Processing rules
   • Open questions

   ORDCALC_design_spec.xlsx

   No	Item	Condition / calculation	Source
   1	Discount rate	Quantity ≥ 100 → 5%	R-01
   2	Discount rate	Customer rank A → +2%	R-02
   3	Order amount	Quantity × unit price × (1 − discount rate), rounded	R-03
   4	Status	Amount > credit limit → 9 (on hold), otherwise 0	R-04

4. STEP 4 / Verification results

   Same input to old and new, then compare

   We feed the same data to the migrated program (for example, Java) and the original COBOL and check that the results match. Any difference is recorded with its cause.

   Same input to old and new, then compare

   NoNo	InputInput	Old (COBOL)Old	New (Java)New	ResultResult
   T1	Qty 99, unit price 1,000, rank B	99,000	99,000	Match
   T2	Qty 100, unit price 1,000, rank B	95,000	95,000	Match
   T3	Qty 100, unit price 1,000, rank A	93,000	93,000	Match
   T4	Qty 150, unit price 333, rank A (rounding)	46,454	46,454	Match
   T5	Same as T2, credit limit 50,000	Status 9	Status 9	Match

   Old = original COBOL, New = migrated program (for example, Java)

   5 of 5 cases match1 open question (U-01) to decide with the customer