/a></li>
	  <li><a href="#national">National histories of legal time</a></li>
	  <li><a href="#costs">Costs and benefits of time shifts</a></li>
	  <li><a href="#precision">Precision timekeeping</a></li>
	  <li><a href="#notation">Time notation</a></li>
	</ul>
      </li>
      <li><a href="#see-also">See also</a></li>
    </ul>
  </nav>

<section>
<h2 id="tzdb">The <code><abbr title="time zone">tz</abbr></code> database</h2>
<p>
The <a href="https://en.wikipedia.org/wiki/Public_domain">public-domain</a>
ti