VT_Xpt
 VT_Ypt
 VT_Zpt
// Coordinates of the Point on the track
   double m_XPointOnTrack ;
   double m_YPointOnTrack ;
   double m_ZPointOnTrack ;

 VT_Xvec
 VT_Yvec
 VT_Zvec
// Unit vector coordinates at the Point on the track
   double m_UXPointOnTrack ;
   double m_UYPointOnTrack ;
   double m_UZPointOnTrack ;

 VT_Mom
// Momentum at the Point on the track
   double m_Momentum ;