recursive SUBROUTINE em_field_custom(ele, param, s_rel, t_rel, orb, local_ref, field, calcd, err_flag, &
                                         calc_potential, use_overlap, grid_allow_s_out_of_bounds, rf_time, used_eles)
  USE bmad_struct
  USE bmad_interface, except_dummy => em_field_custom
  use em_field_interface

  IMPLICIT NONE

  type(ele_struct) :: ele
  type(lat_param_struct) param
  type(coord_struct) orb
  type(em_field_struct) field
  type (ele_pointer_struct), allocatable, optional :: used_eles(:)
  real(rp), intent(in) :: s_rel, t_rel
  logical  out_of_range,local_ref
  logical first/.true./
  logical, optional :: calcd, err_flag, calc_potential, grid_allow_s_out_of_bounds, use_overlap
  character(32) :: r_name = 'em_field_custom'


!R = 3.094353005E9/(c_light/1.e9 * B)

!B = 3.094353005*1.E9/(c_light*R)
!E = B*c = 3.094353005*1.E9/(R)=
! E = 0.435089*1.e9 = 435 MV/m


field%E = [ ele%value(custom_attribute1$),0.0_rp, 0.0_rp ]
field%B = [ 0.0_rp, ele%value(custom_attribute2$), 0.0_rp ]
!print '(a,3es12.4, 1x,6es12.4)',ele%name,field%E, orb%vec  
if(first)then
 print '(a,3es12.4)','field%E',field%E
 print '(a,3es12.4)','field%B',field%B
 first=.false.
endif
  RETURN
END SUBROUTINE em_field_custom