  In the present report, let us adress the issues related to simulation of
decays for particle embodied in full production and decay chains of Monte Carlo
programs set-up for experiments such as at LHC or LC. Both technical issues
related to the way how the events may be stored in event records and issues
related to physics (in particular non-factorizable correlations of the
Einstein-Rosen-Podolsky type) will be reviewed on the basis of practical
examples. We will limit our discussion to the case of tau lepton and W boson
decays, but similar problems (and solutions) may arise also in case of
simulation for other intermediate states or particles. Examples related to
construction of physics observables will be also given. In particular the
method of measuring the CP parity properties of the h-tau-tau coupling at LC
will be explained.
