a <a
href="https://en.wikipedia.org/wiki/C_(programming_language)">C</a>
program that compiles
<code><abbr>tz</abbr></code> source into iCalendar-compatible VTIMEZONE files.
Vzic is freely
available under the <a
href="https://www.gnu.org/copyleft/gpl.html"><abbr>GNU</abbr>
General Public License (<abbr
title="General Public License">GPL</abbr>)</a>.</li>
<li><a
href="https://metacpan.org/release/DateTime-TimeZone">DateTime::TimeZone</a>
contains a script <code>parse_olson</code> that compiles
<code><abbr>tz