What atomic information is accessible in measurements of atomic photoionization? At low photon energy the process is usually described in terms of dipole matrix elements, and it is characterized in terms of a few energy-dependent parameters. In fact quadrupole effects are often not negligible. As energy increases, higher multipole contributions (characterized by additional energy dependent parameters) become important. On the other hand, as energy increases matrix elements are increasingly describable in terms of their small-distance (nuclear point Coulombic) properties. The remaining atomic information at very high energy is, for example, contained in constants such as the bound state normalization constant (i.e. the strength of the bound state wave function at the nucleus). Apart from such constants, nuclear Coulombic matrix elements (including also Coulombic phase shifts) are sufficient to accurately describe atomic photoionization at high energy [1,2], and no further atomic information is obtained in measurement of photoionization at high energies. What information is accessible at lower energies?