[W/K] :: reference counting

  reference counting
       
           A garbage collection technique where each
          memory cell contains a count of the number of other cells
          which point to it.  If this count reaches zero the cell is
          freed and its pointers to other cells are followed to
          decrement their counts, and so on recursively.
       
          This technique cannot cope with circular data structures.
          Cells in such structures refer (indirectly) to themselves and
          so will never have a zero reference count.  This means they
          would never be reclaimed, even when there are no references
          from outside the structure.
       
          (1995-02-22)