  We present the analysis of the 1/Q-suppressed non-perturbative (NP)
contribution to the cumulative out-of-event-plane momentum distribution in e+e-
annihilation in the near-to-planar three-jet region. It complements our
previous study of the perturbative (PT) distributions resummed to single
logarithmic accuracy. Due to inter-jet soft gluon radiation, the NP
contributions (as well as the PT distributions) are sensitive to the geometry
(the angles between jets) and the colour structure of the underlying hard
process (topology of the three-prong parton antenna). The results and
techniques presented here could be extended to other multi-jet processes and,
in particular, to hadron-hadron collisions.
