Regarding ordered quantity and shipped quantity

Hi All,

   As per my understanding of the OM, when the line got shipped , the line level ordered quantity and shipped quantity will be equal for forward flow orders. In case of insufficient number of of items for the order line, the line will split into other with the quantity of insufficient amount as those lines will be backordered, but the parent line will be shipped and the shipped quantity will be equal to ordered quantity. But I observed in our database where ordered quantity is more than shipped quantity and the line is in CLOSED status. I didn't able