eter_base_unit</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="number">0.3048</span><span class="special">);</span>
</pre>
<p>
        Alternately, we could use the SI length <code class="computeroutput"><span class="keyword">typedef</span></code>:
      </p>
<pre class="programlisting"><span class="identifier">BOOST_UNITS_DEFINE_CONVERSION_FACTOR</span><span class="special">(</span><span class="identifier">foot_base_unit</span><span class=