I am trying to create a tar file of assorted Netware files using tar.nlm
and open it later in windows using a Windows tar utility such as 7-zip or
PowerArchiver 6.1.

On NW65SP5 if I run the command:

tar -c -T sys:\system\filestoinclude.txt -f sys:\system\tarfile.tar,

I can successfully create a tar file named tarfile.tar. However, when I
copy it to windows and try to open it with either 7-zip or PowerArchiver,
I get a message stating "Invalid or Unsupported Archive Type." Both of
these utilities reputedly handle tar files.

Any ever do this successfully?