Here the Atiyah-Singer integrand, AS, is the same as before, manufactured from differential-geometric information in the spin structure and auxiliary bundle by local operations. On the other hand the 77-invariant is a global object constructed from б о so fixed purely in terms of boundary data. In fact it is a spectral invariant of б о This decomposition into a ‘local interior’ and a ‘global boundary’ term is fundamental to the utility of the result. 3. Boundary conditions versus ò-geometry.