I thought those files were a compromise when apple went to OS_X and got rid of the old "resource fork" park of the mac OS finder system. This data was part of the file, and let the operating system know which program to open the file with (even if it didn't have a .ext). But it made it hard to interopt.. But I might be a little off.

https://en.wikipedia.org/wiki/Resource_fork

http://mirror.informatimago.com/next/developer.apple.com/doc...