A fast and reliable way to implement these systems in GSTAR is to use
a dedicated geant parser (Fortran preprocessor) which is supported
by an Advanced Geant Interface library called AgSTAR . Maintaining
the GEANT specific tables of materials, volumes, hits descriptions, etc
and insuring the internal consistency of most of the actual parameters
of the GEANT routines, it significantly reduces the amount of information
the user needs to worry about and improves the robustness of the program.
Here we describe the main rules and features of this program.