virtual DOS machine (VDM)

virtual DOS machine (VDM): A protected environment subsystem that emulates MS-DOS and 16-bit Windows within 32-bit versions of the Windows Server 2003 family. A VDM is created whenever a user starts an MS-DOS program in 32-bit versions of the Windows Server 2003 family.

Note that 64-bit versions of the Windows Server 2003 family cannot run MS-DOS and 16-bit Windows programs.