When used with tape drives, Backup Exec uses the Microsoft Tape Format (MTF), which is also used by Windows NTBackup, backup utilities included in Microsoft SQL Server, and many other backup vendors and is compatible with BKF. Microsoft Tape Format (MTF) was originally Maynard's (Backup Exec's first authors) proprietary backup Tape Format (MTF) and was later licensed by Microsoft as Windows standard tape format. In addition, Microsoft also licensed and incorporated Backup Exec's backup engine into Windows NT, the server version of Windows.