How to identify if an AP invoice has been coded using account coding workflow

We have a requirement where we want to create an AP invoice approval rule based on the condition that whether the AP invoice has been coded using the account coding workflow or not. We have an attribute in the ap approval worksheet pertaining to account coding i.e. account coding status. But that would be complete for all the invoices which have been coded either using account coding workflow or have been coded manually i.e. by directly entering the account code combination at line or distribution level.

Kindly assist in providing an attribute which clearly identifies that an AP invoice has been coded using the account coding workflow only, other than the account coding status.