Carrying Out Availability Checks 
You can carry out an availability check either for the entire order or for individual components in the material list.
Checking all Material Components in the Order
To check the availability of all material components in the order, choose Process order
® Functions ® Availability check ® Material - ATP.The system carries out an availability check. If material components are not available on their requirements date, the status "Material shortfall" is set in the process order. A dialog box appears to inform you about this.
Checking Individual Components
To check the availability of a particular material, proceed as follows:
A screen appears on which the quantity required on the requirements date and the confirmed quantity are displayed.
In both cases, you can:
The system only sets the status "Material shortfall" in the process order if you carry out an availability check for all components, that is, for the entire order, and one or more components are not available on their respective requirements dates.
In Customizing, you can specify that process orders with status "Material shortfall" are blocked for release.
For more information, see the R/3 Library PP - Material Requirements Planning under
Availability Check.