Table design stratagem??

[dannyC]

Hello..

I designed a table named receipt_master which include purchase order &
shipping & goods_return header information, with a flags column, they can
be distinguished.
then I designed a receipt_detail table, include all the detailed
information( product_id, qty, unit_price.......) of above receipt...

My question is, should I seperate all the different purpose receipt into
different tables? or keep them together? which is the best stratage for a
selling system...

thanks..

Danny