In Setup and Operation, Budget is the original budget for the expense item, Revised budget is the budget adjusted for change orders to the client, Forecast is the posted amount for closed months plus what is accrued going forward, and Deviation is the difference between the revised budget and the forecast.
The columns
Budget: The original budget for the expense item, usually taken from the production code.
Revised budget adjustment: The difference coming from Change Order Client where setup and operation costs are carried forward and generate revenue. If the column is filled in, there are change orders to the client that generate setup costs.
Revised budget: Budget + revised budget adjustment.
Forecast: Everything posted up to and including the last closed month, plus what is accrued for the months ahead. At project start, forecast and budget are often the same.
Deviation: The difference between the revised budget and the forecast. For a closed month, the deviation also shows the difference between what was accrued and what was actually posted.
Tips
The column layout can be customized. Keep it simple, show only the columns you actually use, and save the layout as a table profile.