Availability Check: Control Parameters 
Availability Check: Control Parameters
Features
In the R/3 standard the control of the availability check is carried out via general control features (such as MRP characteristic and item category, requirements type and requirements class) and sales-specific control features (such as checking rule, check group, schedule line category). You can control via the schedule line category whether an ATP check and a transfer of requirements should take place in sales documents. The settings that are possible at schedule line level depend on the settings in the requirements class, which is deduced via the requirements type of the material. Additionally you can make specific settings for AFS materials in Customizing.
Scope of check
The execution of the ATP check for AFS materials depends on different control factors which may determine, for example, the scope of check. The determination of the scope of check for the ATP check is generally carried out using the checking rule (currently the checking rule in SD is fixed, for the sales order it is
A) and the check group (this is copied from the material master). You can enter for example a search horizon in the AFS-specific settings for every combination of check group/checking rule. As a result, stock and requirements that are beyond the search horizon are not taken into account (see also AFS-specific Settings of the Scope of Check).
Further control possibilities are available including the
Alternative Check Group and Split Indicator to influence the results of the ATP check.AFS Restrictions
During the scope of check the following topics are not supported: