Purchase order qty issue

Hi SAP SD gurus,

I am creating Purchase order with 100 QTY. with reference Purchase order while creating the delivery level to enter the Qty 200. in this case system is allow to create the delivery Qty 200 more than the Purchase Order Qty. in Standard SAP how to restrict the Qty in delivery levle.

Note: When ever to create the delivery qty more than the Purchase order qty it will showing the error Message in delivery levle. where it is controlled ?

Thanks and Regards,

Murali krishna