e class="literal-block">
#include &lt;boost/parameter/keyword.hpp&gt;
</pre>
<p>will ensure <tt class="docutils literal"><span class="pre">boost::parameter::keyword</span></tt> is known to the
compiler.  There is also a combined header,
<tt class="docutils literal">boost/parameter.hpp</tt>, that includes most of the library's
components.  For the the rest of this tutorial, unless we say
otherwise, you can use the rule above to figure out which header
to <tt class="docutils literal">#include</tt> to access a