r">sub_range</span></code> can propagate constness
        because it knows what a corresponding <code class="computeroutput"><span class="identifier">const_iterator</span></code>
        is.
      </p>
<p>
        Both classes can be used as ranges since they implement the <a class="link" href="extending.html" title="Extending the library">minimal
        interface</a> required for this to work automatically.
      </p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width=