  Modern experimental facilities, such as CBELSA, ELPH, JLab, MAMI and SPring-8
have provided a tremendous volume of data, often with wide energy and angular
coverage, and with increasing precision. For reactions with two hadrons in the
final state, these data are often presented as multiple sets of panels, with
angular distributions at numerous specific energies. Such presentations have
limited visual appeal, and their physical content is typically extracted
through some model- dependent treatment. Instead, we explore the use of a
Legendre series expansion with a relatively small number of essential
coefficients. This approach has been applied in several recent experimental
investigations. We present some general properties of the Legendre coefficients
in the helicity framework and consider what physical information can be
extracted without any model-dependent assumptions.
