OTM provides attribute columns (Char, Number, Date, and Currency) on most major transaction tables such as ORDER_RELEASE and SHIPMENT to store custom data alongside standard fields. Flex Fields are definitions applied to these attribute columns that control how the field behaves in the UI — including whether it shows a free-text entry, a query-driven dropdown, or a standard lookup list. Once defined, a Flex Field can be added to a Manager Layout so that users can enter data directly from the screen.