How to fetch past 6 period's values based on user input ?

Hi Experts,

Simple but not simple question . I know how to calculate the fy and fy period value based on user input. but need to know how to calculate for past 6 period's ( 0fiscper3) values based on user input.

I mean, see the user will enter 0fiscyear and 0fiscper3 initially. But the report should show previous 6 period's ( amount) values in different columns'.

I know we can do it through offset based on user input period -1, user input period -2,.......user input period -6. But what if the user input 001. Then how to we create restriction to change the 0fiscyear value to previous year ? Will it automaticaly take the previous period ? I dont think so right.

For example, user input - 0fiscyear = 2010, 0fiscper3=001.

I need 2009.012, 2009.011, 2009.010, 2009.009, 2009.008,2009.007. Do I need a customer exit for this ?

Thank You

DR