I am trying to save bone joints to a file, and am using this format. I was wondering if anyone could clear up a few questions I have

1. why do I need to provide rotation data for the bone, if I already gave it the location?
2. How do I calculate the rotation of each axis if I have the relative location from the parent joint?

** EDIT **

After doing some more digging, I think that it has something to do with quaternions, so, could someone point me to a good resource on using quaternions for bone joints?

** EDIT AGAIN **

I think I've solved it, but I don't understand how it works. I can't seem to find any google results explaining it. I'd appreciate if anyone could send resources explaining it to me.