How to Create Reservation in SAP?

Reservations :Reservations enable you to make sure that the reserved material will be available at a later time for a specific purpose. A reservation for a goods issue can be requested from different departments and for different account assignment objects (for example, cost center, order, asset). Material Requirements Planning takes reservations into account so that required material can be procured in time. Using this app, you can also use reservations as a planning instrument for future goods receipts. You can manually create reservations

To Create Reservation :  MB21
change Reservation   :  MB22
Display Reservation  :  MB23

Create Reservation :  MB21

movement type : 311