Steps:

1.Right-click on a use instruction bar on the resource Gantt chart. The use instruction bar popup menu will be displayed.
2.Select [Operation] – [Edit Operation…] from the use instruction bar popup menu. Properties of the use instruction for the operation you selected will be displayed in the properties window.
3.Select the General tab from the properties window.
4.Specify a quantity for the property “User specified quantity”.
5.The specified production quantity will be considered as a quantity constraint during scheduling.
6.You can specify the user specified quantity for an operation only after Asprova generated the operation from scheduling.