I am making a purchasing plan with pivottable. On column field I have two
status of orders: firmed order and forecast order, and quantity for each
coming months as data.

Now I add a calculated field to calculate the purchasing order for firmed
order, however, that will add the same calculated field to other forecast
order as well, which I don't need it.

How to put a calculated field for one item in column field, but not the
others? Thanks.