  VNI is a general-purpose Monte-Carlo event-generator, which includes the
simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron,
hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution
of parton cascades in conjunction with a self-consistent hadronization scheme,
as well as the development of hadron cascades after hadronization. The causal
evolution from a specific initial state (determined by the colliding beam
particles) is followed by the time-development of the phase-space densities of
partons, pre-hadronic parton clusters, and final-state hadrons, in
position-space, momentum-space and color-space. The parton-evolution is
described in terms of a space-time generalization of the familiar
momentum-space description of multiple (semi)hard interactions in QCD,
involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2
radiation processes. The formation of color-singlet pre-hadronic clusters and
their decays into hadrons, on the other hand, is treated by using a spatial
criterion motivated by confinement and a non-perturbative model for
hadronization. Finally, the cascading of produced pre-hadronic clusters and of
hadrons is includes a multitude of 2 -> n processes, and is modeled in paralell
to the parton cascade description. This paper gives a brief review of the
physics underlying VNI, as well as a detailed description of the program
itself. The latter program description emphasizes easy-to-use pragmatism and
explains how to use the program (including simple examples), annotates input
and control parameters, and discusses output data provided by it.
