Override Cost rate Projects Budget Sheet after 11i.PJ_PF.M

Hi, 

There are additional enhancement on the ADI form used for budget uploads in 11i.PJ_PF.M
Originally there were only 4 data input columns i.e. Quantity, Raw Cost, Burdened Cost and Revenue

Now dthere are 7 data input columns, the additional columns being Override Raw Cost Rate, Override Burdened Cost Rate and Override Bill Rate

Can anyone help with what these additional columns (Override Raw Cost Rate, Override Burdened Cost Rate and Override Bill Rate) are menat for in terms of functionality?

Thanks,