Gravity interpretation involves inversion of data into models, but it is more. Gravity interpretation is used in a "holistic" sense going beyond "inversion". Inversion is like optimization within certain a priori assumptions, i.e., all anticipated models lie in a limited domain of the a priori errors. No source should exist outside the anticipated model volume, but that is never literally true. Interpretation goes beyond by taking "outside" possibilities into account in the widest sense. Any neglected possibility carries the danger of seriously affecting the interpretation. Gravity...