JSI Tip 1285. DOSONLY.

When you exit an MS-DOS application, Windows NT returns to CMD.exe.

When you suspend an MS-DOS application (or run a TSR), Windows NT returns to COMMAND.COM (unless you specify Ntcmdprompt in your Config.NT). COMMAND.COM preserves the MS-DOS environment.

If you run an non MS-DOS application, it will disrupt the MS-DOS environment. To prevent this, place the DOSONLY command in Config.NT or the config specified in your shortcut.

DOSONLY prevents COMMAND.COM from starting anything other than MS-DOS applications.