Q: What the hidden file in /Library/Application Support directory   for?

Hello valkudry,

There is no way to tell from a directory listing. You would have to inspect the contents. Even then it might not be possible to tell. Apps often use hidden files like this for license codes and other home-grown DRM strategies.

A bigger question is where you found that great old-school DOS directory browser. It reminds me of the great Cathode Terminal app (https://itunes.apple.com/us/app/cathode/id499233976?mt=12) or the Blinky text editor (https://itunes.apple.com/us/app/blinky/id550873221?mt=12) by the same author.