Most data structures in \cgal\ use the concept of \ccc{Handle} in their user
interface to refer to the elements they store.  This concept describes what is
sometimes called a trivial iterator.  A \ccc{Handle} is akeen to a pointer to
an object providing the dereference operator \ccc{operator*()} and member
access \ccc{operator->()} but no increment or decrement operators like
iterators.  A \ccc{Handle} is intended to be used whenever the referenced
object is not part of a logical sequence.