Originally Posted by antonvaltaz
And to be fair, Microsoft Office 2007 and Open Office file formats are zips with an XML definition - I think that's an increasingly common way to define file formats.
While it's not excatly a zip, I get your idea. A file format would have a different header and structure than a zip file. It's more a (zip) file definition and if the XML file in it contains infos about the WinUAE config, I see it's use. If it doesn't however, it's a mere zip with some overhead