Carnegie Mellon Software Engineering Institute, a federal research center, won a $994.9 million U.S. Air Force contract add-on for software development related to national defense, the Pentagon said Tuesday.

No details of the work were disclosed in the Defense Department's daily contract digest. A representative of the engineering institute did not immediately return a phone call seeking comment. The contracting was handled by Hanscom Air Force Base in Massachusetts, the notice said.

(Reporting by Jim Wolf, editing by Bernard Orr)