Final answer:
A user can be restricted from removing line items that are added to the configuration through a Recommended Item rule by adding an Advanced Validation rule on the Delete Main Doc Action, ensuring all parts come from a 'mandatory' rule, or using a Constraint rule to throw a runtime error on the Delete Action event.
Step-by-step explanation:
A user can be restricted from removing line items that are added to the configuration through a Recommended Item rule by adding an Advanced Validation rule on the Delete Main Doc Action. This rule can check if the line item is part of a Recommended Item rule and prevent its deletion. For example, the rule can compare the line item's ID with the IDs of all line items added through the Recommended Item rule and display an error message if there is a match.
Another way to restrict the removal of line items is by ensuring that all parts are coming from a 'mandatory' Recommended Item rule. This means that the Recommended Item rule must be set as mandatory, and the system will not allow the removal of any line items added through this rule.
Alternatively, a Constraint rule can be written to throw a runtime error on the Delete Action event. This rule can be set to check if the line item belongs to a Recommended Item rule and display an error message if an attempt is made to delete it.