  In the future high energy physics experiments, the question of properly
matching the phenomenological programs that describe different parts of the
physics processes (such as hard scattering, hadronization, decay of resonances,
detector response, etc.) is very important. In the past, FORTAN common blocks
filled with lists of objects (particles, strings, clusters, etc.) of defined
properties, origins and descendants were in use. Similar structures are now
envisaged, for future programs, to be written in languages such as C++ or Java.
  From the physics point of view such an approach is not correct, since this
kind of data structures impose certain approximations on the physics content.
In the present paper, we will explore their limits, using examples from the
physics of W's, tau's and the Higgs boson, still to be discovered.
