diff --git a/tracy/tracy/inc/tracy_global.h b/tracy/tracy/inc/tracy_global.h
index 781bbdfcb29136ed5f64060a28d8fccb07afce2d..afca82afe57dd1cb230451ebccc22c5904e618bb 100644
--- a/tracy/tracy/inc/tracy_global.h
+++ b/tracy/tracy/inc/tracy_global.h
@@ -103,13 +103,13 @@ struct MpoleType {
   mpolArray   PBrnd;     // random scale factor of rms error PBrms
   mpolArray   PB;        // total field strength(design,sys,rms)
   int         Porder;    // The highest order in PB
-  int         n_design;  // multipole order (design)
+  int         n_design;  // multipole order (design, All = 0, Dip = 1, Quad = 2, Sext = 3, Oct = 4, Dec = 5, Dodec = 6)
   pthicktype  Pthick;    // thick element
   // Bending Angles
   double PTx1;           // horizontal entrance angle [deg]
   double PTx2;           // horizontal exit angle [deg]
   double Pgap;           // total magnet gap [m] 
-  double Pirho;          // angle/strength of the dipole, 1/rho [1/m] 
+  double Pirho;          // angle([radian], but in lattice definition, angle is with unit degree)/length of the dipole, 1/rho [1/m] 
   double Pc0, Pc1, Ps1;  // corrections for roll error of bend 
   Matrix AU55,           // Upstream 5x5 matrix 
     AD55;           // Downstream 5x5 matrix