"official" file format?

Is there some list of "officially recognized" file formats? Or is just whatever is whatever?

There you go:

http://www.google.co.uk/search?q=fil...ient=firefox-a

Edit: not sure what you mean by officially recognised

Well, there's file formats that have been standardized by an official national or international standards organization, like ODF by the ISO.

There's file formats that have been standardized by an unofficial industry consortium, like XML by the W3C, or OOXML by the ECMA.

Or you could simply talk about formats that have a recognized media type registered with the IANA.
http://www.iana.org/assignments/media-types/

I've used http://www.wotsit.org/ for this in the past.

Yeah, ISO specified formats is what I was thinking of.