anchor.diff:  
       use bl_constants_module, only: ZERO, HALF, TWO
       use meth_params_module, only: NVAR, URHO, UTEMP
  -    use prob_params_module, only: center, probhi
  +    use prob_params_module, only: center, probhi, dim, Symmetry, physbc_lo, physbc_hi
       use probdata_module, only: max_tagging_radius, &
                                  max_stellar_tagging_level, &
                                  max_temperature_tagging_level, &
  
positive.code: 
               ! Clear all tagging that occurs outside the radius set by max_tagging_radius.
  
               r = ((x-center(1))**2 + (y-center(2))**2 + (z-center(3))**2)**HALF
  
               if (r .gt. max_tagging_radius * maxval(abs(problo-center)) .or. &
                    r .gt. max_tagging_radius * maxval(abs(probhi-center)) ) then
  
                  tag(i,j,k) = clear
  
               endif
  
               ! We must ensure that the outermost zones are untagged due to the Poisson equation boundary conditions.
               ! This is necessary in addition to the above step because the problem center doesn't always coincide with the geometric center.
  
               if (x .lt. problo(1) + TWO * dx(1) .or. x .gt. probhi(1) - TWO * dx(1) .or. &
                    y .lt. problo(2) + TWO * dx(2) .or. y .gt. probhi(2) - TWO * dx(2) .or. &
                    z .lt. problo(3) + TWO * dx(3) .or. z .gt. probhi(3) - TWO * dx(3)) then
  
                  tag(i,j,k) = clear
  
  
negative.code:                    ! radius to ensure there aren't any sharp gradients in regions of
                     ! greater than ambient density.
  
                     r_P = ( sum((loc-com_P)**2) )**HALF
                     r_S = ( sum((loc-com_S)**2) )**HALF
  
                     if (r_P <= roche_tagging_factor * roche_rad_P) then
                        tag(i,j,k) = set
  