For your purposes, you probably need to update the IV10001 table. The only work tables with the Reason_Code field are:
IV10001 - Inventory Transaction Amounts Work
IV10004 - Inventory Bin Quantity Transfer
IV10301 - Stock Count Line
For your purposes, you probably need to update the IV10001 table. The only work tables with the Reason_Code field are:
IV10001 - Inventory Transaction Amounts Work
IV10004 - Inventory Bin Quantity Transfer
IV10301 - Stock Count Line