Others have mentioned the "plain text files" thing, so let me just mention the "plain text files" thing.<p>Everything is stored as a plain text file. It's just text. Hell, it's practically human-readable, if you're a fairly nerdy human.<p>You can store them in git, or any other source code repository. You can email them or stick them up on a server, without them getting mangled, because they're just text.<p>You can run scripts on them, or just plain open them in a text editor and do search-and-replace on them.<p>You can even write code to write files for you - take a bunch of stuff and programmatically design footprints and components, any way you like, because it's just plain text files, describing lines and co-ordinates and stuff.<p>Can't get any less locked-in than that!