I'm using the citation program Zotero (although I'm not sure if this problem is actually Zotero-specific).
When I click a link of the format file:\\\\\\C:\\... within this program, the "Launch Application" window pops up. There is a program called "file" which seems to work for all file links. They are opened with the standard program chosen on my computer.

A colleague of mine doesn't have this "file" option in her "Launch Application" window. So I tried different other programs to find out what this mysterious "file" program might be (see attached image; I tried regedit and explorer). Explorer seems to work for most, but not all cases of links.
My question is: What could this "file" program be? Is this some kind of executable? Or is this just a Zotero-specific thing that happens to appear in the "Launch Application" window while it is not actually a program?