The Optimize process will automatically pass required data to the Proposed Contacts Table (PCT), including the audience key fields, the assigned offer(s), and the contact date. Additional fields may be required in the PCT, such as channel or cost per offer, which you must populate by mapping to an existing field. You may use any mapped table field or derived field. Derived fields are useful to pass a constant text string, for example, the channel "Call Center - Midwest".