  The influence of the initial-state structure and the reaction mechanism on
three-body decays is investigated by example of the 6Be continuum populated in
neutron-knockout reactions on 7Be. The sensitivity of the 6Be excitation
spectrum and the three-body correlations to the different components of the
model is demonstrated. It is shown that the spin composition of the initial
state may have an overwhelming effect on the three-body continuum. The
characteristics and structure of the second $0^+_2$ and $2^+_2$ states in 6Be
are predicted for the first time and the conditions for their reliable
observations are formulated. The effects of interference and the alignment of
three-body states on the three-body correlations are demonstrated.
