  We derive expressions for the scattering, extinction and conversion of the
chirality of monochromatic light scattered by bodies which are characterized by
a T-matrix. In analogy to the conditions obtained from the conservation of
energy, these quantities enable the classification of arbitrary scattering
objects due to their full, i.e. either chiral or achiral, electromagnetic
response. To this end, we put forward and determine the concepts of duality and
breaking of duality symmetry, anti-duality, helicity variation, helicity
annhiliation and the breaking of helicity annihilation. Different classes, such
as chiral and dual scatterers, are illustrated in this analysis with model
examples of spherical and non-spherical shape. As for spheres, these concepts
are analysed by considering non-Rayleigh dipolar dielectric particles of high
refractive index, which, having a strong magnetic response to the incident
wavefield, offer an excellent laboratory to test and interpret such changes in
the chirality of the illumination. In addition, comparisons with existing
experimental data are made.
