Substitution Preselection Settings
To activate the preselection of suitable substitutions (substitution preselection), you must make the following settings:
...
● When assigning a rule strategy or rule strategy sequence, set the Preselectnindicator.
● Make all of the settings for the rule-based availability check that are necessary to determine rules. If you want to influence rule determination as part of substitution preselection, select the Preselect field in the field catalog.

To determine a substitution list, during substitution preselection, the system evaluates all substitutions in all the determined rules. This can have a negative effect on performance. To improve performance, we recommend that you use rules with few substitutions for substitution preselection.
● In the check instructions, select one of the following values for substitution preselection:
○ Preselection Active
○ Preselection Can Be Switched On Externally
When you select this value, you can trigger substitution preselection from the OLTP system.
■ Trigger substitution preselection from SAP CRM
In SAP Customer Relationship Management (SAP CRM), assign the requirements profile from the global ATP check to the item categories.
In the requirements profile, set the Preselectionindicator. For more information, see the Implementation Guide (IMG) for SAP SCM under Advanced Planning and Optimization → Global Available-to-Promise (Global ATP) → General Settings → Maintain Requirements Profile.
On the
initial screen for the
simulative ATP
check, set the Substitution Presel. Active
indicator.
■ Trigger substitution preselection from a different OLTP system
Select the Preselct. field in the field catalog of the OLTP system.
For more information, see the Implementation Guide (IMG) for SAP Supply Chain Management (SAP SCM) under Advanced Planning and Optimization → Global Available-to-Promise (Global ATP) → General Settings → Maintain Check Instructions.