!
      subroutine minor(tn,o2,ox,n2,he,w,difkk,fin,fnm,fhd,flbc,fubc,
     |  sloss,sprod,small,rmass,phix,alfax,xy,ilbc,iubc,fout,fout_nm,
     |  lev0,lev1,lon0,lon1,lat0,lat1,idebug)
!
! Advances minor species by one time step.
!
! Lower boundary:
!   If ilbc == 0, then
!     flbc(1) = A, flbc(2) = B, flbc(3) = C, where A*DPSX/DZ + B*PSX + C = 0.
!   If ilbc == 1,      (not the normal case)
!     flbc(3) = total upward number flux of F at lower boundary.
!
! Upper boundary:
!   If iubc == 0, then
!     fubc = diffusive upward number flux of F at upper boundary.
!   If iubc == 1, then
!     fubc = total upward number flux of F at upper boundary.
!   If iubc == 2, then
!     fubc = value of PSX at upper boundary.
!
! Sources:
!   sloss = Sx/n(x), where sx is portion of number density
!           source proportional to n(x), the minor species number
!           density     (level k+1/2)
!   sprod = Portion of number density source independent
!           of n(x).    (level k+1/2)
!
      use params_module,only: nlonp4,dz
      use lbc,only: b,fb
      use cons_module,only: rmassinv_o2,rmassinv_ox,rmassinv_n2,p0,
     |  expz,expzmid,expzmid_inv,boltz,rmass_o2,rmass_ox,rmass_n2,
     |  dtx2inv,grav,avo,dtsmooth,dtsmooth_div2,shapiro,rmassinv_he
      use input_module,only: difhor
      use fields_module,only: tlbc
      use addfld_module,only: addfld
#ifdef MPI
      use mpi_module,only: mp_bndlons_f3d, mp_periodic_f3d
#endif
      implicit none
!
! Input Args:
      integer,intent(in) :: lev0,lev1,lon0,lon1,lat0,lat1,iubc,ilbc,
     |  idebug
      real,dimension(lev0:lev1,lon0-2:lon1+2,lat0-2:lat1+2),intent(in)::
     |  tn,o2,ox,n2,he,w,difkk,fin,fnm,fhd
      real,dimension(lev0:lev1,lon0:lon1,lat0:lat1),intent(in)::
     |  sloss,  ! portion of number density source proportional to minor sp s1,s14
     |  sprod   ! portion of number density source independent of minor sp  s2,s15
      real,dimension(lon0:lon1),intent(in) ::
     |  flbc(lon0:lon1,3,lat0:lat1), ! 3 components of lower boundary
     |  fubc(lon0:lon1,lat0:lat1)    ! upper boundary
      real,intent(in) :: rmass,phix(3),alfax,small(lev1-lev0+1),xy
!
! Output Args:
      real,dimension(lev0:lev1,lon0-2:lon1+2,lat0-2:lat1+2),
     |  intent(out) :: fout,fout_nm