s NewRounding&gt;
struct change_rounding {
  typedef ... type;
};

template&lt;class OldInterval, class NewChecking&gt;
struct change_checking {
  typedef ... type;
};

template&lt;class OldInterval&gt;
struct unprotect {
  typedef ... type;
};

} // namespace interval_lib
} // namespace numeric
} // namespace boost</pre>

<p>The <code>policies</code> template should be used whenever the user needs
to define a policy structure for an <code>interval</code> class.
<code>change_rounding</code> and <code>change