QQMA0014 (SAP documentation) - When saving notifications, this customer enhancement allows you to carry out inspections and to supplement missing values.
IWOC0002 (SAP Documentation) - Furthermore, the customer exit enables field checks to be made in the current notification and allows the status change dependent on the inspection result.
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As per the above SAP documentation, it has been mentioned that checks can be done for the missing values. Check with your ABAP consultants.