In CMSIM we use the extended list of particles which is given in the following table:
Table 3.1: The list of particles used in CMSIM.
The main reason for this extension is to provide the possibility for the weak decay of particles, including the simulation of their decay vertex inside GEANT via a call to GUDCAY/LU1ENT/LUEXEC/LUDECY (see program flow in section 2.4).