As far as I know, you can look into the file with a hexeditor (maybe any other editor should do it, too).
In the first line is written, which OS is required. However, there could be anything written, but in most cases it is set correctly. Please do not blame me, if I am wrong, but I blieve, this is known as the "mime header". But I am not sure, how this one can be trusted in the Windows world. In linux, the mime-header is the basics of recognition of the kind of data, there are no endings needed or analyzed. Best regards Hans
