\section{Introduction}
The program {\it g2\_tracking} propagates charged particles into and around the g-2 ring. The guide field, 
including M5 line, injection channel and storage ring, is modelled using element types defined
in the \href{http://www.lepp.cornell.edu/~dcs/bmad/}{\it BMAD} 
programming language. {\it g2\_{tracking}} is assembled largely from routines in the {\it BMAD} 
(fortran) subroutine library. 


 
