The structure of the Sun's interior will be studied by inverting frequencies of normal modes of solar oscillation, accurate measurements of which will be obtained in the Medium-l Program. The inversions will be done at two levels: `primary' inversions that deal with the hydrostatic properties (pressure, density and the adiabatic exponent) of the spherically-symmetric component of the solar structure, and `secondary' inversions that include additional assumptions about the equation of state. It is also possible to test uncertainties in the additional assumptions with helioseismic inversions. However, the principal objective of the Team Science Working Group is to perform the `primary' and some basic `secondary' inversions. The mathematical techniques of the inversions are developed on the basis of general inverse theory. Most of the specific secondary inversions will be carried out by Science Working Groups which will also develop novel inversion techniques.
The results of the Medium-l and Structure Inversions Programs will be shared with other helioseismology groups.