So someone has sent you a file format for which you have no idea where it belongs? Ever had that happen?

I have often found myself looking at a file format which does not make sense to me. For example, what is a file with the format name of ".emf"?

If you have exhausted other ways of finding out what that format name refers to, then possibly you need to go and visit with the site "Almost Every file format in the world!" and you will find that an ".emf" is an "Enhanced Windows Metafile".

What about an ".ewl" (Microsoft encarta Document) or a ".jff" (JPEG bitmap)?

Yes, all of these and many hundreds more can be found on this page of file formats.