Thank you for your willingness to help make NumPy the best array system available. The only rules we like to follow are to try hard to keep the SVN repository in a buildable state and to not indiscriminately muck with what others have contributed. Simple changes and obvious improvements are always welcome. Changes that fundamentally change behavior need discussion on numpy-discussions@scipy.org before anything is done. Please add meaningful comments when you check changes in. These comments form the basis of the change-log. Add unit tests to excercise new code, and regression tests whenever you fix a bug.