Denial for a Commercial Loan

In regards to the check box options on an adverse action notice, as a commercial lender, I would like to add “Length of time in business is too short” as we do deny credit to many newly established companies (per our credit policy), so my question is this: Can I create my own reason(s) or are there a specific set of reasons that I need to adhere to? Where does ‘length of time in business too short’ (or verbiage to that effect) fit on an adverse action notice?