Presettings for the Availability Check 
Presettings for the Availability Check
The availability check basically runs the same during rescheduling as during the order creation. All of the (R/3 standard and AFS-specific) control features are valid that you have executed for each material master, checking rule, item and/or schedule line categories, and so on.
Please note, however, that the availability check runs in the background during rescheduling. A few functions or options are therefore only limitedly or not at all available to you depending on the process flow. A few special presettings are therefore necessary.
Selection from Various Delivery Proposals (ATP Overview Screen)
During the order entry in the dialog, the system goes to a special ATP overview screen in the case of a stock shortage if the appropriate setting has been made. Here you can select from different delivery proposals (one-time delivery, total quantity, delivery proposal).
You must make this decision ahead of time to have the availability check run in the background. You carry out this control per sales document type for each sales area.
To do this choose in SD Customizing Sales ® Sales Documents ® Sales Document Headers ® Maintain Sales Document Types per Sales Area for AFS.
In the case of a requirement for which a sufficient quantity cannot be met by the requested delivery date, you control how that requirement will be handled during rescheduling, based on what you enter in the field ATP run proposal.
The total requirement quantity is confirmed for incoming stock on several different dates. This means that the schedule line is split and the original requirement quantity is distributed proportionately over different delivery dates.
Please take note that you can only carry out a schedule line split if you have permitted this in Customizing in the superior item category. For each item category, select the field Splitting ind. in SD Customizing under Sales ® Sales Documents ® Sales Document Items ® Maintain Item Categories for AFS.
The requirement is confirmed in the full quantity for the date of the next incoming stock or for the end of the replenishment lead time.
The requirement is confirmed for the requested delivery date in the quantity in which stock is available on this date. The remaining requirement quantity is rejected.
Material / Plant Substitution during the Availability Check
This function is only possible during the order entry in the dialog.