MAT calculation

Dear Friends/ Experts,

I have a book profit of Rs. 8,00,000/- for last F.Y.

Further, in past years from AY 2010-11 to AY 2014- 2015 i had book losses. Also, i had depreciation for each of the years.. The depreciation for each year was less than, book losses for each year.

In MAT deduction coloum, there is a section which mentions Bought forward business loss or depreciation whichever is lower... Which loss are they talking about (as per I.T.Act or book losses)