Challenging one Regarding layouts in Report

Dear all,

I am developing a report using function modules.Here in my report i want a feature of VA05.In VA05 if we goto SETTINGS->LAYOUT->CHOOSE.It will allow us to select a layout. If we select header level layout it will display all records without duplicates.Again if we select item level layout it will display records with duplicates.Can anybody tell me how can i implement this logic in my report.

Regards,

vineel