Non-Final Office Action
An Office action letter that raises new issues and usually is the first phase of the examination process. An examining attorney will issue a non-final Office action after reviewing the application for the first time. If a new issue arises after the applicant responds to the first non-final Office action, the examining attorney will issue another non-final Office action that sets forth the new issue(s) and continues any that remain outstanding. Applicants must respond to non-final Office action letters within 6 months from the date they are issued to avoid abandonment of the application.
Source: U.S. Patent and Trademark Office.