bill, that's probably the best explanation I've seen so far, thanks. It sounds like that's kind of hard to comply with though, no? So I'll need a binary of my original program somewhere so people can modify the open source libraries and link to it? I can kind of see how that works with normal C programming, but in the context of arduino, I'm a little confused. I've never really seen a 'binary' or object code to somehow stick in an arduino compiler with some open source libraries available for me to play with.