The parameters of the particles transported by GEANT are stored in the data structure JPART via the routine GSPART. The decay properties of particles are defined via the routine GSDK. The particle constants can be accessed with the routine GFPART and printed with the routine GPPART.
The routine GPART defines the standard table of particles, branching ratios and decay modes. This routine needs to be called for the GEANT system to work properly. GPART calls the routine GSPART for the particle properties and GSDK for the decays for each particle in the standard GEANT table. The user may call GSPART and GSDK to extend or modify the table defined by GPART.