You may redistribute this, or use it in packs, or pretty much do anything you would like with it. If you use this, I would like you to contact me, and let me know, though you don't have to. If you belong to the official Thermal Expansion team, you may do, literally, whatever you want with your local copy of this mod, including modifying it and redistributing it. If you want the source code, please contact me. Although I imagine you know exactly what I'm doing.