>>HI Vidar!
>>
>>In Windows NT workstation 4.0 result of OS() is DOS 05.00
>
>So we can't use OS() to determine if the Fox DOS app is running on NT, just that it's running on DOS?

My fault...I had a moment of brain deadness and didn't notice that you said in DOS. How about the GETENV() function? You could check comspec and see if it includes "WINNT" in the string. I realize it's not 100% reliable, but it's close since the vast majority of people don't change where NT puts its files. If comspec doesn't work, look for any environment variable that would normally have WINNT in it or if it uses CMD.EXe versus COMMAND.COM. There are also other environment variables which could be useful.

Christopher