constraint_eqn_012 Subroutine

   subroutine constraint_eqn_012(tmp_cc, tmp_con, tmp_err, tmp_symbol, tmp_units)
      !! Equation for volt-second capability lower limit
      !! author: P B Lloyd, CCFE, Culham Science Centre
      !! args : output structure : residual error; constraint value;
      !! residual error in physical units; output string; units string
      !! Equation for volt-second capability lower limit
      !! #=# pfcoil
      !! #=#=# fvs, vsstt
      !! and hence also optional here.
      !! Logic change during pre-factoring: err, symbol, units will be assigned only if present.
      !! vsstt : input real : total V-s needed (Wb)
      !! vsstt (lower limit) is positive; vstot (available) is negative
      !! fvs : input real : f-value for flux-swing (V-s) requirement (STEADY STATE)
      !! vstot : input real :   total flux swing for pulse (Wb)
      use physics_variables, only: vsstt
      use constraint_variables, only: fvs
      use pfcoil_variables, only: vstot
      implicit none
            real(dp), intent(out) :: tmp_cc
      real(dp), intent(out) :: tmp_con
      real(dp), intent(out) :: tmp_err
      character(len=1), intent(out) :: tmp_symbol
      character(len=10), intent(out) :: tmp_units

      tmp_cc =  1.0D0 + fvs * vstot/vsstt
      tmp_con = vsstt * (1.0D0 - tmp_cc)
      tmp_err = vsstt * tmp_cc
      tmp_symbol = '>'
      tmp_units = 'V.sec'

   end subroutine constraint_eqn_012