Thanks for the quick response. I fully agree with that approach however, I cannot alter the application... I could make the field required but there is no place for the user to input. here is the basic scenario:

We have an application that is lacking in the audit trailing area for data changes. My boss wants me to create an audit trail to capture who changed the value of a specific column, when and the old and new values from the change. Pretty standard stuff for an audit trail... then he throws the curve ball. He also wants the database to send the user a form and force them to give a reason for the change and if they don't provide a reason then roll back the transaction. If they do then commit the change and log it to the audit trail with the user provided comments as to why they made the change. making matters more difficult the application is compiled and we cant change the code. They dont want to work with the vendor of the application for they will charge us.