anchor.diff:        enddo
   
   c     # Face 2
  -      do jbc = 1-mbc,mint
  -         do i = mint+1,mx+mbc
  +      do jbc = 0,mint
  +         do i = mint+1,mx+1
               if (packdata) then
                  qpack(k) = area(i,jbc)
               else
  
positive.code:       enddo
  
  c     # Face 1
        do j = mint+1,my+mbc
           do ibc = mx-mint+1,mx+mbc
              if (packdata) then
                 qpack(k) = area(ibc,j)
              else
  
negative.code:          enddo
  
  c        # Face 3
           do jbc = my-mint+1,my+1
              do i = 0,mx-mint
                 if (packdata) then
                    qpack(k) = qdata(i,jbc,mq)
                 else
  