How to restrict users from entering incorrect date (DFF ) on the purchase requisition lines.

Summary:

The customer has created a DFF Value set . The DFF Value set has been configured in the Manage Requisition Descriptive Flex fields at Distribution line level as Contract Start Date and Contract End Date.

How to restrict users from entering incorrect date with back date or a validation to the contract end date field on the purchase requisition so that the contract end date can’t be less than the contract start date.