Hi again Eric. I spent a bit more time this morning examining behavior on Windows again and it seems like the fallback behavior for /O is actually /O:GN. The E would be redundant and essentially overridden by N.
I'm not quite sure how I would write a test for this case. Probably need to do something like create a known directory structure, pipe the DIR output to a file and then read/analyze the contents. Would need to ignore lines containing the volume name and serial number, etc.
I had already closed the merge request over the weekend but it looks like I might be able to reopen again when changes are ready. Hopefully it will be intuitive to associate the later changes with this request.