The tracking facility offers you an overview of the various documents related to a particular business case.
Tracking shows how sales orders, production orders and purchase orders are related to the manufacturing order through the reservations.
Open the 
Firm Planned Prod.
Order window.
Select a firm planned production order.
Select the production order line you want to track.
Click Functions, Order Tracking. The lines in the Order Tracking window display the documents that are related to the current production order line.
Reserving Items for Production Order Lines
Reserving Items for Production Order Components
Amending or Canceling Item Reservations