  The initial-state jet matching method introduced in our previous studies has
been applied to the event generation of single $W$ and $Z$ production processes
and diboson ($W^{+}W^{-}$, $WZ$ and $ZZ$) production processes at hadron
collisions in the framework of the GR@PPA event generator. The generated events
reproduce the transverse momentum spectra of weak bosons continuously in the
entire kinematical region. The matrix elements (ME) for hard interactions are
still at the tree level. As in previous versions, the decays of weak bosons are
included in the matrix elements. Therefore, spin correlations and phase-space
effects in the decay of weak bosons are exact at the tree level. The program
package includes custom-made parton shower programs as well as ME-based hard
interaction generators in order to achieve self-consistent jet matching. The
generated events can be passed to general-purpose event generators to make the
simulation proceed down to the hadron level.
