Log Message:
Import pythia-6.4.25 as wip/pythia6.

The Pythia program can be used to generate high-energy-physics events,
i.e. sets of outgoing particles produced in the interactions between two in-
coming particles. The objective is to provide as accurate as possible a
representation of event properties in a wide range of reactions, within and
beyond the Standard Model, with emphasis on those where strong inter-
actions play a role, directly or indirectly, and therefore multihadronic final
states are produced. The physics is then not understood well enough to
give an exact description; instead the program has to be based on a com-
bination of analytical results and various QCD-based models. This physics
input is summarized here, for areas such as hard subprocesses, initial- and
final-state parton showers, underlying events and beam remnants, fragmen-
tation and decays, and much more. Furthermore, extensive information is
provided on all program elements: subroutines and functions, switches and
parameters, and particle and process data