same combination of base units as <code class="computeroutput"><span class="identifier">Unit2</span></code> and if <code class="computeroutput"><span class="identifier">Y</span></code>
            and <code class="computeroutput"><span class="identifier">Z</span></code> are convertible.
          </li>
<li class="listitem">
            assignment between <code class="computeroutput"><span class="identifier">quantity</span><span class="special">&lt;</span><span class="identifier">Unit1</span><span class="spe