On 5 October 2015 at 17:42, Kare Nuorteva <kare.nuorteva@me.com> wrote:

> Could someone please explain what is a frog in a filename?


It's many decades old, and not restricted to file names. It originally
referred to an unexpected non-ASCII character in a text file:
"There's a frog in my file!" It was sometimes put there by a buggy editor
or corrupt file system. By extension it's a
character, still usually unprintable (before Unicode fonts), that doesn't
belong in its context. It's a bit of a stretch to call "/" a frog,
but that's just the name of the array.