  An extensive program for the calculation of galactic cosmic-ray propagation
has been developed. This is a continuation of the work described in Strong &
Youssefi (1995). The main motivation for developing this code is the prediction
of diffuse Galactic gamma rays for comparison with data from the CGRO
instruments EGRET, COMPTEL, and OSSE. The basic spatial propagation mechanisms
are (momentum-dependent) diffusion, convection, while in momentum space energy
loss and diffusive reacceleration are treated. Primary and secondary nucleons,
primary and secondary electrons, and secondary positrons are included.
Fragmentation and energy losses are computed using realistic distributions for
the interstellar gas and radiation fields.
  This study indicates that it is possible to construct a model satisfying a
wide range of observational constraints and provides a basis for future
developments.
