Windows NT 3.51 build 980

Windows NT 3.51 build 980.1 is an unleaked build of Windows NT 3.51, mentioned in the file  from the Windows NT 4.0 source code.

; Beginning with NT 3.51 (build 980 or so), the front of the export table
 * contains a signature and an export-table-version number. This allows
 * a DOS DLL to tell whether it has been loaded by an older application.