anchor.diff:  c      write(6,*) 'Doing x=sweep : blockno = ', blockno
         do  j = 2-mbc,my+mbc-1
   c     
  -c     # copy data along a slice into 1d arrays:
  +c        # copy data along a slice into 1d arrays:
            do m=1,meqn
               do i = 1-mbc, mx+mbc
                  q1d(i,m) = qold(i,j,m)
  
positive.code: c     
  c     #
  c     # update fluxes for use in AMR:
  c     
           do  m=1,meqn
              do  j=2-mbc,my+mbc
                 gm(i,j,m) = gm(i,j,m) + faddm(j,m)
  
negative.code: 
           cflgrid = dmax1(cflgrid,cfl1d)
  c     
  c        # update fluxes for use in AMR:
  c        # NOTE : We update ghost cell values for subcycling
           do  m=1,meqn
              do  i=2-mbc,mx+mbc
                 fm(i,j,m) = fm(i,j,m) + faddm(i,m)
  