.bak One line Back-up Files

You might see *.bak files in you project folder when the oneline is not closed properly or is corrupted. These files may occupy lot of space on the hard drive. You can delete these files safely without affecting your projects. If your original oneline is corrupt, you can rename the *.bak to *.drw.

Normally, you will not see *.bak files if the oneline are closed without any problem. PTW will automatically remove these *.bak files.